<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/include, branch v6.18.46</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>drm/client: Remove drm_client_framebuffer_delete()</title>
<updated>2026-08-23T12:27:09+00:00</updated>
<author>
<name>Thomas Zimmermann</name>
<email>tzimmermann@suse.de</email>
</author>
<published>2025-10-27T12:09:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a6325e2807dc2b985a2fea363794e0ed52e02698'/>
<id>a6325e2807dc2b985a2fea363794e0ed52e02698</id>
<content type='text'>
[ Upstream commit 3e3153325fd3693d0f9fe235c4afbcd68ef102e1 ]

Release client buffers with drm_client_buffer_delete() instead of
drm_client_framebuffer_delete(). The latter is just a tiny wrapper
around the former.

Move the test for !buffer into drm_client_buffer_delete(), although
all callers appear to always have a valid pointer.

v2:
- test for !buffer before deref-ing pointer (Jocelyn, Dan)

Signed-off-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Reviewed-by: Jocelyn Falempe &lt;jfalempe@redhat.com&gt;
Tested-by: Francesco Valla &lt;francesco@valla.it&gt;
Link: https://patch.msgid.link/20251027121042.143588-6-tzimmermann@suse.de
Stable-dep-of: f4f2bba28df9 ("drm/log: Fix infinite loop when scale is too large for display")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 3e3153325fd3693d0f9fe235c4afbcd68ef102e1 ]

Release client buffers with drm_client_buffer_delete() instead of
drm_client_framebuffer_delete(). The latter is just a tiny wrapper
around the former.

Move the test for !buffer into drm_client_buffer_delete(), although
all callers appear to always have a valid pointer.

v2:
- test for !buffer before deref-ing pointer (Jocelyn, Dan)

Signed-off-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Reviewed-by: Jocelyn Falempe &lt;jfalempe@redhat.com&gt;
Tested-by: Francesco Valla &lt;francesco@valla.it&gt;
Link: https://patch.msgid.link/20251027121042.143588-6-tzimmermann@suse.de
Stable-dep-of: f4f2bba28df9 ("drm/log: Fix infinite loop when scale is too large for display")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/client: Deprecate struct drm_client_buffer.gem</title>
<updated>2026-08-23T12:27:09+00:00</updated>
<author>
<name>Thomas Zimmermann</name>
<email>tzimmermann@suse.de</email>
</author>
<published>2025-10-27T12:09:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=329731b3119f0cd3fe68f650f844462dad4895e8'/>
<id>329731b3119f0cd3fe68f650f844462dad4895e8</id>
<content type='text'>
[ Upstream commit ea39f2e66e61035e203530977a3df428345d03e2 ]

The client buffer's framebuffer holds a reference and pointer on
each of its GEM buffer objects. Thus the field gem in the client-
buffer struct is not necessary. Deprecated the field and convert
the client-buffer helpers to use the framebuffer's objects.

In drm_client_buffer_delete(), do a possible vunmap before releasing
the framebuffer. Otherwise we'd eventually release the framebuffer
before unmaping its buffer objects.

v2:
- avoid dependency on CONFIG_DRM_KMS_HELPER

Signed-off-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Reviewed-by: Jocelyn Falempe &lt;jfalempe@redhat.com&gt;
Tested-by: Francesco Valla &lt;francesco@valla.it&gt;
Link: https://patch.msgid.link/20251027121042.143588-5-tzimmermann@suse.de
Stable-dep-of: f4f2bba28df9 ("drm/log: Fix infinite loop when scale is too large for display")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit ea39f2e66e61035e203530977a3df428345d03e2 ]

The client buffer's framebuffer holds a reference and pointer on
each of its GEM buffer objects. Thus the field gem in the client-
buffer struct is not necessary. Deprecated the field and convert
the client-buffer helpers to use the framebuffer's objects.

In drm_client_buffer_delete(), do a possible vunmap before releasing
the framebuffer. Otherwise we'd eventually release the framebuffer
before unmaping its buffer objects.

v2:
- avoid dependency on CONFIG_DRM_KMS_HELPER

Signed-off-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Reviewed-by: Jocelyn Falempe &lt;jfalempe@redhat.com&gt;
Tested-by: Francesco Valla &lt;francesco@valla.it&gt;
Link: https://patch.msgid.link/20251027121042.143588-5-tzimmermann@suse.de
Stable-dep-of: f4f2bba28df9 ("drm/log: Fix infinite loop when scale is too large for display")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/client: Remove pitch from struct drm_client_buffer</title>
<updated>2026-08-23T12:27:09+00:00</updated>
<author>
<name>Thomas Zimmermann</name>
<email>tzimmermann@suse.de</email>
</author>
<published>2025-10-27T12:09:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=841bc853a2b115457d980891a44e64c5122f7bca'/>
<id>841bc853a2b115457d980891a44e64c5122f7bca</id>
<content type='text'>
[ Upstream commit dce4657ff526b65007fe8d5c92968a933cc7c9da ]

Only the client-buffer setup uses the pitch field from struct
drm_client_buffer. Remove the field and pass the value among setup
helpers.

Clients that need the pitch should rather look at the framebuffer's
pitches[0] directly.

Signed-off-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Reviewed-by: Jocelyn Falempe &lt;jfalempe@redhat.com&gt;
Tested-by: Francesco Valla &lt;francesco@valla.it&gt;
Link: https://patch.msgid.link/20251027121042.143588-2-tzimmermann@suse.de
Stable-dep-of: f4f2bba28df9 ("drm/log: Fix infinite loop when scale is too large for display")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit dce4657ff526b65007fe8d5c92968a933cc7c9da ]

Only the client-buffer setup uses the pitch field from struct
drm_client_buffer. Remove the field and pass the value among setup
helpers.

Clients that need the pitch should rather look at the framebuffer's
pitches[0] directly.

Signed-off-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Reviewed-by: Jocelyn Falempe &lt;jfalempe@redhat.com&gt;
Tested-by: Francesco Valla &lt;francesco@valla.it&gt;
Link: https://patch.msgid.link/20251027121042.143588-2-tzimmermann@suse.de
Stable-dep-of: f4f2bba28df9 ("drm/log: Fix infinite loop when scale is too large for display")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ata: libata-scsi: terminate deferred commands on time out</title>
<updated>2026-08-23T12:27:05+00:00</updated>
<author>
<name>Damien Le Moal</name>
<email>dlemoal@kernel.org</email>
</author>
<published>2026-08-11T01:10:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=4c8d7595a10a630bc7ab8b017ca88944f92b39b0'/>
<id>4c8d7595a10a630bc7ab8b017ca88944f92b39b0</id>
<content type='text'>
[ Upstream commit 2e1d2e65e773d67dab163127f11a47dab0fbca9f ]

If a command times out while we have deferred non-NCQ commands waiting to
be issued, the SCSI EH task is not immediately woken up as the waiting
deferred commands are never issued nor completed, thus leaving the SCSI
host in a busy state (shost-&gt;host_failed != scsi_host_busy(shost)) which
prevents the SCSI EH task from being woken up. Eventually, when the
deferred commands also time out, the SCSI EH task is woken up and the
timeout processing occurs.

Avoid this unnecessary SCSI EH task wake-up additional time by scheduling
a retry of all waiting deferred QCs, using the eh_timed_out SCSI host
template operation. The function ata_scsi_eh_timed_out() is introduced to
implement this operation.

However, terminating deferred commands with DID_REQUEUE to force a retry
by calling the function ata_scsi_requeue_deferred_qc() may still keep the
SCSI host in a busy state because the block layer may immediately re-issue
these commands. The solution to this is to schedule libata EH for the
port which suffered the command timeout to prevent accepting any new
command. ata_scsi_requeue_deferred_qc() is modified to add a call to
ata_port_schedule_eh() for this purpose.

In addition to this change, ata_scsi_requeue_deferred_qc() is also
modified to take a new timedout_scmd scsi command argument which indicates
the SCSI command that timed out. With this additional argument,
ata_scsi_requeue_deferred_qc() can now also terminate with DID_TIME_OUT
any timed out deferred qc, which simplifies ata_scsi_cmd_error_handler().
In this case, ata_scsi_requeue_deferred_qc() returns SCSI_EH_DONE, with
this return value propagated back to the ata_scsi_eh_timed_out() operation
to indicate to scsi_timeout() that the timed out command was handled and
no further processing is needed.

For non-timed out deferred qc that need to be retried,
ata_scsi_requeue_deferred_qc() returns SCSI_EH_NOT_HANDLED, thus
indicating to scsi_timeout() that the timed out command needs to go
through the SCSI EH (and libata EH) processing by adding it to the EH work
queue with scsi_eh_scmd_add().

One side effect of these changes is that the function atapi_qc_complete()
needs to be modified to ensure that a deferred ATAPI command that needs
to be retried is completed with DID_REQUEUE instead of the default
SAM_STAT_GOOD status, and a command that timed out is completed with
DID_TIME_OUT instead of SAM_STAT_CHECK_CONDITION.

Fixes: 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal &lt;dlemoal@kernel.org&gt;
Reviewed-by: Igor Pylypiv &lt;ipylypiv@google.com&gt;
Tested-by: Igor Pylypiv &lt;ipylypiv@google.com&gt;
Reviewed-by: Niklas Cassel &lt;cassel@kernel.org&gt;
Reviewed-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 2e1d2e65e773d67dab163127f11a47dab0fbca9f ]

If a command times out while we have deferred non-NCQ commands waiting to
be issued, the SCSI EH task is not immediately woken up as the waiting
deferred commands are never issued nor completed, thus leaving the SCSI
host in a busy state (shost-&gt;host_failed != scsi_host_busy(shost)) which
prevents the SCSI EH task from being woken up. Eventually, when the
deferred commands also time out, the SCSI EH task is woken up and the
timeout processing occurs.

Avoid this unnecessary SCSI EH task wake-up additional time by scheduling
a retry of all waiting deferred QCs, using the eh_timed_out SCSI host
template operation. The function ata_scsi_eh_timed_out() is introduced to
implement this operation.

However, terminating deferred commands with DID_REQUEUE to force a retry
by calling the function ata_scsi_requeue_deferred_qc() may still keep the
SCSI host in a busy state because the block layer may immediately re-issue
these commands. The solution to this is to schedule libata EH for the
port which suffered the command timeout to prevent accepting any new
command. ata_scsi_requeue_deferred_qc() is modified to add a call to
ata_port_schedule_eh() for this purpose.

In addition to this change, ata_scsi_requeue_deferred_qc() is also
modified to take a new timedout_scmd scsi command argument which indicates
the SCSI command that timed out. With this additional argument,
ata_scsi_requeue_deferred_qc() can now also terminate with DID_TIME_OUT
any timed out deferred qc, which simplifies ata_scsi_cmd_error_handler().
In this case, ata_scsi_requeue_deferred_qc() returns SCSI_EH_DONE, with
this return value propagated back to the ata_scsi_eh_timed_out() operation
to indicate to scsi_timeout() that the timed out command was handled and
no further processing is needed.

For non-timed out deferred qc that need to be retried,
ata_scsi_requeue_deferred_qc() returns SCSI_EH_NOT_HANDLED, thus
indicating to scsi_timeout() that the timed out command needs to go
through the SCSI EH (and libata EH) processing by adding it to the EH work
queue with scsi_eh_scmd_add().

One side effect of these changes is that the function atapi_qc_complete()
needs to be modified to ensure that a deferred ATAPI command that needs
to be retried is completed with DID_REQUEUE instead of the default
SAM_STAT_GOOD status, and a command that timed out is completed with
DID_TIME_OUT instead of SAM_STAT_CHECK_CONDITION.

Fixes: 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal &lt;dlemoal@kernel.org&gt;
Reviewed-by: Igor Pylypiv &lt;ipylypiv@google.com&gt;
Tested-by: Igor Pylypiv &lt;ipylypiv@google.com&gt;
Reviewed-by: Niklas Cassel &lt;cassel@kernel.org&gt;
Reviewed-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: replace pmd_to_swp_entry() with softleaf_from_pmd()</title>
<updated>2026-08-23T12:27:04+00:00</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2026-08-10T10:57:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ea563ed2b10ae35a3122a7dafd82f070e4bed2c4'/>
<id>ea563ed2b10ae35a3122a7dafd82f070e4bed2c4</id>
<content type='text'>
[ Upstream commit 0ac881efe16468503e8c1e7d8a7210b75f027ce3 ]

Introduce softleaf_from_pmd() to do the equivalent operation for PMDs that
softleaf_from_pte() fulfils, and cascade changes through code base
accordingly, introducing helpers as necessary.

We are then able to eliminate pmd_to_swp_entry(),
is_pmd_migration_entry(), is_pmd_device_private_entry() and
is_pmd_non_present_folio_entry().

This further establishes the use of leaf operations throughout the code
base and further establishes the foundations for eliminating
is_swap_pmd().

No functional change intended.

[lorenzo.stoakes@oracle.com: check writable, not readable/writable, per Vlastimil]
  Link: https://lkml.kernel.org/r/cd97b6ec-00f9-45a4-9ae0-8f009c212a94@lucifer.local
Link: https://lkml.kernel.org/r/3fb431699639ded8fdc63d2210aa77a38c8891f1.1762812360.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Reviewed-by: SeongJae Park &lt;sj@kernel.org&gt;\
Reviewed-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Alexander Gordeev &lt;agordeev@linux.ibm.com&gt;
Cc: Alistair Popple &lt;apopple@nvidia.com&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Axel Rasmussen &lt;axelrasmussen@google.com&gt;
Cc: Baolin Wang &lt;baolin.wang@linux.alibaba.com&gt;
Cc: Baoquan He &lt;bhe@redhat.com&gt;
Cc: Barry Song &lt;baohua@kernel.org&gt;
Cc: Byungchul Park &lt;byungchul@sk.com&gt;
Cc: Chengming Zhou &lt;chengming.zhou@linux.dev&gt;
Cc: Chris Li &lt;chrisl@kernel.org&gt;
Cc: Christian Borntraeger &lt;borntraeger@linux.ibm.com&gt;
Cc: Christian Brauner &lt;brauner@kernel.org&gt;
Cc: Claudio Imbrenda &lt;imbrenda@linux.ibm.com&gt;
Cc: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Dev Jain &lt;dev.jain@arm.com&gt;
Cc: Gerald Schaefer &lt;gerald.schaefer@linux.ibm.com&gt;
Cc: Gregory Price &lt;gourry@gourry.net&gt;
Cc: Heiko Carstens &lt;hca@linux.ibm.com&gt;
Cc: "Huang, Ying" &lt;ying.huang@linux.alibaba.com&gt;
Cc: Hugh Dickins &lt;hughd@google.com&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Janosch Frank &lt;frankja@linux.ibm.com&gt;
Cc: Jason Gunthorpe &lt;jgg@ziepe.ca&gt;
Cc: Joshua Hahn &lt;joshua.hahnjy@gmail.com&gt;
Cc: Kairui Song &lt;kasong@tencent.com&gt;
Cc: Kemeng Shi &lt;shikemeng@huaweicloud.com&gt;
Cc: Lance Yang &lt;lance.yang@linux.dev&gt;
Cc: Leon Romanovsky &lt;leon@kernel.org&gt;
Cc: Liam Howlett &lt;liam.howlett@oracle.com&gt;
Cc: Mathew Brost &lt;matthew.brost@intel.com&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Naoya Horiguchi &lt;nao.horiguchi@gmail.com&gt;
Cc: Nhat Pham &lt;nphamcs@gmail.com&gt;
Cc: Nico Pache &lt;npache@redhat.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Pasha Tatashin &lt;pasha.tatashin@soleen.com&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Rakie Kim &lt;rakie.kim@sk.com&gt;
Cc: Rik van Riel &lt;riel@surriel.com&gt;
Cc: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Sven Schnelle &lt;svens@linux.ibm.com&gt;
Cc: Vasily Gorbik &lt;gor@linux.ibm.com&gt;
Cc: Wei Xu &lt;weixugc@google.com&gt;
Cc: xu xin &lt;xu.xin16@zte.com.cn&gt;
Cc: Yuanchu Xie &lt;yuanchu@google.com&gt;
Cc: Zi Yan &lt;ziy@nvidia.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Stable-dep-of: 4165b7d1c45c ("userfaultfd: wait on source PMD during UFFDIO_MOVE")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 0ac881efe16468503e8c1e7d8a7210b75f027ce3 ]

Introduce softleaf_from_pmd() to do the equivalent operation for PMDs that
softleaf_from_pte() fulfils, and cascade changes through code base
accordingly, introducing helpers as necessary.

We are then able to eliminate pmd_to_swp_entry(),
is_pmd_migration_entry(), is_pmd_device_private_entry() and
is_pmd_non_present_folio_entry().

This further establishes the use of leaf operations throughout the code
base and further establishes the foundations for eliminating
is_swap_pmd().

No functional change intended.

[lorenzo.stoakes@oracle.com: check writable, not readable/writable, per Vlastimil]
  Link: https://lkml.kernel.org/r/cd97b6ec-00f9-45a4-9ae0-8f009c212a94@lucifer.local
Link: https://lkml.kernel.org/r/3fb431699639ded8fdc63d2210aa77a38c8891f1.1762812360.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Reviewed-by: SeongJae Park &lt;sj@kernel.org&gt;\
Reviewed-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Alexander Gordeev &lt;agordeev@linux.ibm.com&gt;
Cc: Alistair Popple &lt;apopple@nvidia.com&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Axel Rasmussen &lt;axelrasmussen@google.com&gt;
Cc: Baolin Wang &lt;baolin.wang@linux.alibaba.com&gt;
Cc: Baoquan He &lt;bhe@redhat.com&gt;
Cc: Barry Song &lt;baohua@kernel.org&gt;
Cc: Byungchul Park &lt;byungchul@sk.com&gt;
Cc: Chengming Zhou &lt;chengming.zhou@linux.dev&gt;
Cc: Chris Li &lt;chrisl@kernel.org&gt;
Cc: Christian Borntraeger &lt;borntraeger@linux.ibm.com&gt;
Cc: Christian Brauner &lt;brauner@kernel.org&gt;
Cc: Claudio Imbrenda &lt;imbrenda@linux.ibm.com&gt;
Cc: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Dev Jain &lt;dev.jain@arm.com&gt;
Cc: Gerald Schaefer &lt;gerald.schaefer@linux.ibm.com&gt;
Cc: Gregory Price &lt;gourry@gourry.net&gt;
Cc: Heiko Carstens &lt;hca@linux.ibm.com&gt;
Cc: "Huang, Ying" &lt;ying.huang@linux.alibaba.com&gt;
Cc: Hugh Dickins &lt;hughd@google.com&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Janosch Frank &lt;frankja@linux.ibm.com&gt;
Cc: Jason Gunthorpe &lt;jgg@ziepe.ca&gt;
Cc: Joshua Hahn &lt;joshua.hahnjy@gmail.com&gt;
Cc: Kairui Song &lt;kasong@tencent.com&gt;
Cc: Kemeng Shi &lt;shikemeng@huaweicloud.com&gt;
Cc: Lance Yang &lt;lance.yang@linux.dev&gt;
Cc: Leon Romanovsky &lt;leon@kernel.org&gt;
Cc: Liam Howlett &lt;liam.howlett@oracle.com&gt;
Cc: Mathew Brost &lt;matthew.brost@intel.com&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Naoya Horiguchi &lt;nao.horiguchi@gmail.com&gt;
Cc: Nhat Pham &lt;nphamcs@gmail.com&gt;
Cc: Nico Pache &lt;npache@redhat.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Pasha Tatashin &lt;pasha.tatashin@soleen.com&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Rakie Kim &lt;rakie.kim@sk.com&gt;
Cc: Rik van Riel &lt;riel@surriel.com&gt;
Cc: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Sven Schnelle &lt;svens@linux.ibm.com&gt;
Cc: Vasily Gorbik &lt;gor@linux.ibm.com&gt;
Cc: Wei Xu &lt;weixugc@google.com&gt;
Cc: xu xin &lt;xu.xin16@zte.com.cn&gt;
Cc: Yuanchu Xie &lt;yuanchu@google.com&gt;
Cc: Zi Yan &lt;ziy@nvidia.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Stable-dep-of: 4165b7d1c45c ("userfaultfd: wait on source PMD during UFFDIO_MOVE")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ipvs: separate destination availability state</title>
<updated>2026-08-23T12:26:54+00:00</updated>
<author>
<name>Yizhou Zhao</name>
<email>zhaoyz24@mails.tsinghua.edu.cn</email>
</author>
<published>2026-08-18T20:16:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1a4c3ffe2a48b8023e744fda201afcc758a5b37f'/>
<id>1a4c3ffe2a48b8023e744fda201afcc758a5b37f</id>
<content type='text'>
commit cdcc4e46180df8161f4d2f3c6fd6beaf6990133d upstream.

IPVS configuration paths update destination availability while connection
accounting updates destination overload state. The two independent states
share dest-&gt;flags, so their read-modify-write updates can race and lose one
another.

Keep OVERLOAD in flags, where the preceding patch serializes its updates
with dst_lock, and move AVAILABLE to cflags. This keeps configuration-
controlled availability out of the scheduler hot cacheline until a
scheduler needs to check it. It also prevents availability updates from
clobbering overload state.

The destination status bits are not exposed through the IPVS sockopt or
netlink interfaces, so keep their definitions in the internal IPVS header.

Readers can still observe stale destination state; this does not provide a
cross-field snapshot.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Reported-by: Yizhou Zhao &lt;zhaoyz24@mails.tsinghua.edu.cn&gt;
Reported-by: Yuxiang Yang &lt;yangyx22@mails.tsinghua.edu.cn&gt;
Reported-by: Ao Wang &lt;wangao@seu.edu.cn&gt;
Reported-by: Xuewei Feng &lt;fengxw06@126.com&gt;
Reported-by: Qi Li &lt;qli01@tsinghua.edu.cn&gt;
Reported-by: Ke Xu &lt;xuke@tsinghua.edu.cn&gt;
Link: https://lore.kernel.org/all/8913381c-1e02-35c7-0ec4-61de5a12fd35@ssi.bg/
Assisted-by: Claude-Code:GLM-5.2
Suggested-by: Julian Anastasov &lt;ja@ssi.bg&gt;
Signed-off-by: Yizhou Zhao &lt;zhaoyz24@mails.tsinghua.edu.cn&gt;
Acked-by: Julian Anastasov &lt;ja@ssi.bg&gt;
Signed-off-by: Pablo Neira Ayuso &lt;pablo@netfilter.org&gt;
(cherry picked from commit cdcc4e46180df8161f4d2f3c6fd6beaf6990133d)
[ Julian: Backport by removing the hunks from ip_vs_xmit.c ]
Signed-off-by: Julian Anastasov &lt;ja@ssi.bg&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit cdcc4e46180df8161f4d2f3c6fd6beaf6990133d upstream.

IPVS configuration paths update destination availability while connection
accounting updates destination overload state. The two independent states
share dest-&gt;flags, so their read-modify-write updates can race and lose one
another.

Keep OVERLOAD in flags, where the preceding patch serializes its updates
with dst_lock, and move AVAILABLE to cflags. This keeps configuration-
controlled availability out of the scheduler hot cacheline until a
scheduler needs to check it. It also prevents availability updates from
clobbering overload state.

The destination status bits are not exposed through the IPVS sockopt or
netlink interfaces, so keep their definitions in the internal IPVS header.

Readers can still observe stale destination state; this does not provide a
cross-field snapshot.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Reported-by: Yizhou Zhao &lt;zhaoyz24@mails.tsinghua.edu.cn&gt;
Reported-by: Yuxiang Yang &lt;yangyx22@mails.tsinghua.edu.cn&gt;
Reported-by: Ao Wang &lt;wangao@seu.edu.cn&gt;
Reported-by: Xuewei Feng &lt;fengxw06@126.com&gt;
Reported-by: Qi Li &lt;qli01@tsinghua.edu.cn&gt;
Reported-by: Ke Xu &lt;xuke@tsinghua.edu.cn&gt;
Link: https://lore.kernel.org/all/8913381c-1e02-35c7-0ec4-61de5a12fd35@ssi.bg/
Assisted-by: Claude-Code:GLM-5.2
Suggested-by: Julian Anastasov &lt;ja@ssi.bg&gt;
Signed-off-by: Yizhou Zhao &lt;zhaoyz24@mails.tsinghua.edu.cn&gt;
Acked-by: Julian Anastasov &lt;ja@ssi.bg&gt;
Signed-off-by: Pablo Neira Ayuso &lt;pablo@netfilter.org&gt;
(cherry picked from commit cdcc4e46180df8161f4d2f3c6fd6beaf6990133d)
[ Julian: Backport by removing the hunks from ip_vs_xmit.c ]
Signed-off-by: Julian Anastasov &lt;ja@ssi.bg&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/psi: Create the psimon kthread outside of cgroup_mutex</title>
<updated>2026-08-19T16:18:20+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>tj@kernel.org</email>
</author>
<published>2026-07-12T17:23:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=102fb2dacf4500617be9bc2105c1ee6f17151455'/>
<id>102fb2dacf4500617be9bc2105c1ee6f17151455</id>
<content type='text'>
commit fadeedd7cfc5d73d33fa3d7ac54b9b27aabd09d2 upstream.

a5b98009f16d ("sched/psi: fix race between file release and pressure write")
made pressure_write() hold cgroup_mutex across psi_trigger_create(), which
forks the psimon kthread for the first rtpoll trigger. As kthread creation
depends on the whole fork path, the commit inadvertently created a lot of
unwanted locking dependencies from cgroup_mutex.

sched_ext got hit by one: its enable path blocks forks and then grabs
cgroup_mutex, so a pressure write racing a scheduler enable deadlocks, with
every other fork piling up behind.

Fix it by splitting trigger creation so that the worker is forked with
cgroup_mutex dropped and the kernfs active reference left broken. The latter
matters because rmdir and cgroup.pressure writes drain active references
under cgroup_mutex. Publishing the trigger last keeps error reporting
synchronous and preserves the of-&gt;priv lifetime rules.

The trigger registered in the first stage pins the group's rtpoll machinery
across the unlocked window, leaving only creation races to resolve. The
catch-up poll on installation covers scheduling attempts dropped while there
was no worker.

v2: Retagged sched/psi (was cgroup).

Fixes: a5b98009f16d ("sched/psi: fix race between file release and pressure write")
Cc: stable@vger.kernel.org
Cc: Edward Adam Davis &lt;eadavis@qq.com&gt;
Cc: Chen Ridong &lt;chenridong@huaweicloud.com&gt;
Reported-by: Matt Fleming &lt;mfleming@cloudflare.com&gt;
Closes: https://lore.kernel.org/all/20260710100441.2653477-1-matt@readmodwrite.com/
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Tested-by: Matt Fleming &lt;mfleming@cloudflare.com&gt;
Acked-by: Suren Baghdasaryan &lt;surenb@google.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit fadeedd7cfc5d73d33fa3d7ac54b9b27aabd09d2 upstream.

a5b98009f16d ("sched/psi: fix race between file release and pressure write")
made pressure_write() hold cgroup_mutex across psi_trigger_create(), which
forks the psimon kthread for the first rtpoll trigger. As kthread creation
depends on the whole fork path, the commit inadvertently created a lot of
unwanted locking dependencies from cgroup_mutex.

sched_ext got hit by one: its enable path blocks forks and then grabs
cgroup_mutex, so a pressure write racing a scheduler enable deadlocks, with
every other fork piling up behind.

Fix it by splitting trigger creation so that the worker is forked with
cgroup_mutex dropped and the kernfs active reference left broken. The latter
matters because rmdir and cgroup.pressure writes drain active references
under cgroup_mutex. Publishing the trigger last keeps error reporting
synchronous and preserves the of-&gt;priv lifetime rules.

The trigger registered in the first stage pins the group's rtpoll machinery
across the unlocked window, leaving only creation races to resolve. The
catch-up poll on installation covers scheduling attempts dropped while there
was no worker.

v2: Retagged sched/psi (was cgroup).

Fixes: a5b98009f16d ("sched/psi: fix race between file release and pressure write")
Cc: stable@vger.kernel.org
Cc: Edward Adam Davis &lt;eadavis@qq.com&gt;
Cc: Chen Ridong &lt;chenridong@huaweicloud.com&gt;
Reported-by: Matt Fleming &lt;mfleming@cloudflare.com&gt;
Closes: https://lore.kernel.org/all/20260710100441.2653477-1-matt@readmodwrite.com/
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Tested-by: Matt Fleming &lt;mfleming@cloudflare.com&gt;
Acked-by: Suren Baghdasaryan &lt;surenb@google.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>dibs: initialise dibs-&gt;lock in dibs_dev_alloc()</title>
<updated>2026-08-19T16:18:18+00:00</updated>
<author>
<name>Hidayath Khan</name>
<email>hidayath@linux.ibm.com</email>
</author>
<published>2026-07-30T12:42:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fe79571f40434b257d68cbfb7b3ae93a794d8a11'/>
<id>fe79571f40434b257d68cbfb7b3ae93a794d8a11</id>
<content type='text'>
commit c27e360545373b7aee9862a5beef3b9fb3df0c25 upstream.

dibs-&gt;lock is initialised by dibs_dev_add(), but a dibs device can
already take interrupts before that call: ism_probe() runs
ism_dev_init(), and hence request_irq(), before it calls
dibs_dev_add(). No client can have registered a dmb at that point, so
no dmb interrupt can occur, but a GID event interrupt can, and
ism_handle_irq() takes dibs-&gt;lock unconditionally on entry, before it
inspects anything else.

Initialise the lock in dibs_dev_alloc() instead, so that it is valid as
soon as a driver can publish the device to its interrupt handler.

Fixes: cc21191b584c ("dibs: Move data path to dibs layer")
Cc: stable@vger.kernel.org
Reviewed-by: Alexandra Winter &lt;wintera@linux.ibm.com&gt;
Signed-off-by: Hidayath Khan &lt;hidayath@linux.ibm.com&gt;
Link: https://patch.msgid.link/20260730124227.167829-1-hidayath@linux.ibm.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit c27e360545373b7aee9862a5beef3b9fb3df0c25 upstream.

dibs-&gt;lock is initialised by dibs_dev_add(), but a dibs device can
already take interrupts before that call: ism_probe() runs
ism_dev_init(), and hence request_irq(), before it calls
dibs_dev_add(). No client can have registered a dmb at that point, so
no dmb interrupt can occur, but a GID event interrupt can, and
ism_handle_irq() takes dibs-&gt;lock unconditionally on entry, before it
inspects anything else.

Initialise the lock in dibs_dev_alloc() instead, so that it is valid as
soon as a driver can publish the device to its interrupt handler.

Fixes: cc21191b584c ("dibs: Move data path to dibs layer")
Cc: stable@vger.kernel.org
Reviewed-by: Alexandra Winter &lt;wintera@linux.ibm.com&gt;
Signed-off-by: Hidayath Khan &lt;hidayath@linux.ibm.com&gt;
Link: https://patch.msgid.link/20260730124227.167829-1-hidayath@linux.ibm.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net/sched: act_gact, act_police: range check the fallback control action</title>
<updated>2026-08-19T16:18:18+00:00</updated>
<author>
<name>Hyunjung Ko</name>
<email>hj351016@gmail.com</email>
</author>
<published>2026-08-06T10:12:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=92f00f1d4d204a428b38e26fce3baee144b6955d'/>
<id>92f00f1d4d204a428b38e26fce3baee144b6955d</id>
<content type='text'>
commit 883b56ae58fe657d8497806c7059646e9ba6dbd0 upstream.

tcf_action_check_ctrlact() range checks the primary control action:

	if (!opcode)
		ret = action &gt; TC_ACT_VALUE_MAX ? -EINVAL : 0;

TC_ACT_VALUE_MAX is TC_ACT_TRAP, so kernel-internal verdicts above it
cannot be set that way. But act_gact and act_police each carry a second,
independent control action supplied by user space that never reaches that
helper - TCA_GACT_PROB.paction and TCA_POLICE_RESULT. Both only reject
TC_ACT_GOTO_CHAIN, so any other value is stored verbatim and returned
verbatim from the action.

In particular user space can store TC_ACT_CONSUMED, which is
TC_ACT_VALUE_MAX + 1 and is deliberately not part of the UAPI value
range. That verdict tells every caller the action took ownership of the
skb, so nobody frees it: sch_handle_ingress(), sch_handle_egress() and
tcf_qevent_handle() all deliberately skip the free for it. The result is
one leaked sk_buff plus its data buffer per packet traversing the filter,
unbounded, for all traffic on the chain including kernel-generated
packets.

Both are trivially deterministic. act_gact clamps tcfg_pval to &gt;= 1, so
with pval = 1 gact_determ() returns the fallback for every packet.
act_police has no mandatory rate, so rate = 0 leaves tcfp_mtu = ~0 and
tcf_police_mtu_check() always passes.

TC_ACT_CONSUMED was added by commit 720f22fed81b ("net: sched: refactor
reinsert action"), after both goto-chain guards were written:
commit 9469f375ab09 ("net/sched: act_gact: disallow 'goto chain' on
fallback control action") and
commit c08f5ed5d625 ("net/sched: act_police: disallow 'goto chain' on
fallback control action"). Neither guard was widened when the new
verdict appeared.

Factor the existing range test out of tcf_action_check_ctrlact() as
tcf_action_valid() and apply it to both fallbacks. The helper cannot call
tcf_action_check_ctrlact() directly because that also allocates a
goto_chain, which is exactly what these two sites must not do.

Reproduced on v7.2-rc6: kmemleak reports one leaked 232-byte
skbuff_head_cache object plus its 704-byte data buffer per packet. With
this patch both configurations are rejected with -EINVAL and kmemleak
reports none.

Fixes: 720f22fed81b ("net: sched: refactor reinsert action")
Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Hyunjung Ko &lt;hj351016@gmail.com&gt;
Acked-by: Jamal Hadi Salim &lt;jhs@mojatatu.com&gt;
Tested-by: Victor Nogueira &lt;victor@mojatatu.com&gt;
Link: https://patch.msgid.link/20260806101252.809593-1-hj351016@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 883b56ae58fe657d8497806c7059646e9ba6dbd0 upstream.

tcf_action_check_ctrlact() range checks the primary control action:

	if (!opcode)
		ret = action &gt; TC_ACT_VALUE_MAX ? -EINVAL : 0;

TC_ACT_VALUE_MAX is TC_ACT_TRAP, so kernel-internal verdicts above it
cannot be set that way. But act_gact and act_police each carry a second,
independent control action supplied by user space that never reaches that
helper - TCA_GACT_PROB.paction and TCA_POLICE_RESULT. Both only reject
TC_ACT_GOTO_CHAIN, so any other value is stored verbatim and returned
verbatim from the action.

In particular user space can store TC_ACT_CONSUMED, which is
TC_ACT_VALUE_MAX + 1 and is deliberately not part of the UAPI value
range. That verdict tells every caller the action took ownership of the
skb, so nobody frees it: sch_handle_ingress(), sch_handle_egress() and
tcf_qevent_handle() all deliberately skip the free for it. The result is
one leaked sk_buff plus its data buffer per packet traversing the filter,
unbounded, for all traffic on the chain including kernel-generated
packets.

Both are trivially deterministic. act_gact clamps tcfg_pval to &gt;= 1, so
with pval = 1 gact_determ() returns the fallback for every packet.
act_police has no mandatory rate, so rate = 0 leaves tcfp_mtu = ~0 and
tcf_police_mtu_check() always passes.

TC_ACT_CONSUMED was added by commit 720f22fed81b ("net: sched: refactor
reinsert action"), after both goto-chain guards were written:
commit 9469f375ab09 ("net/sched: act_gact: disallow 'goto chain' on
fallback control action") and
commit c08f5ed5d625 ("net/sched: act_police: disallow 'goto chain' on
fallback control action"). Neither guard was widened when the new
verdict appeared.

Factor the existing range test out of tcf_action_check_ctrlact() as
tcf_action_valid() and apply it to both fallbacks. The helper cannot call
tcf_action_check_ctrlact() directly because that also allocates a
goto_chain, which is exactly what these two sites must not do.

Reproduced on v7.2-rc6: kmemleak reports one leaked 232-byte
skbuff_head_cache object plus its 704-byte data buffer per packet. With
this patch both configurations are rejected with -EINVAL and kmemleak
reports none.

Fixes: 720f22fed81b ("net: sched: refactor reinsert action")
Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Hyunjung Ko &lt;hj351016@gmail.com&gt;
Acked-by: Jamal Hadi Salim &lt;jhs@mojatatu.com&gt;
Tested-by: Victor Nogueira &lt;victor@mojatatu.com&gt;
Link: https://patch.msgid.link/20260806101252.809593-1-hj351016@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ipv6: prevent in6_dev_get() from resurrecting inet6_dev</title>
<updated>2026-08-19T16:18:17+00:00</updated>
<author>
<name>Kyle Zeng</name>
<email>kylebot@openai.com</email>
</author>
<published>2026-08-03T12:27:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=680fbd7942185448eadb990a3d10a53eb946b702'/>
<id>680fbd7942185448eadb990a3d10a53eb946b702</id>
<content type='text'>
commit 0e243671bc7b8eaf00f83dd2f4367436dc0cff98 upstream.

in6_dev_get() reads dev-&gt;ip6_ptr under RCU and then unconditionally
increments its refcount. Device teardown can clear the pointer and drop
the last reference between these operations. The increment then
resurrects an object whose RCU free has already been queued, so callers
can use it after it is freed.

Use refcount_inc_not_zero() and return NULL when the object has already
reached zero. RCU keeps the memory accessible through the attempted
reference acquisition, and a successful increment pins the object for
the caller.

An independent run on the exact unpatched 6f5156d7a31a (v7.2-rc3)
kernel reproduced the invalid reference acquisition as UID 1000:

  refcount_t: addition on 0; use-after-free.
  ip6_mc_source+0xef4/0x17e0

It was followed by the corresponding reference underflow in
ip6_mc_source(). The supplied trace from the same unpatched revision
additionally shows the access after the RCU read-side section ends:

  BUG: KASAN: slab-use-after-free in mutex_lock+0x76/0xe0
  Write of size 8 at addr ffff888015b50240 by task poc/1219

Bug found and triaged by OpenAI Security Research and
validated by Trail of Bits.

Fixes: 8814c4b53381 ("[IPV6] ADDRCONF: Convert addrconf_lock to RCU.")
Cc: stable@vger.kernel.org
Signed-off-by: Kyle Zeng &lt;kylebot@openai.com&gt;
Co-developed-by: David Lee &lt;david.lee@trailofbits.com&gt;
Signed-off-by: David Lee &lt;david.lee@trailofbits.com&gt;
Reviewed-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Link: https://patch.msgid.link/20260803122758.666112-1-david.lee@trailofbits.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 0e243671bc7b8eaf00f83dd2f4367436dc0cff98 upstream.

in6_dev_get() reads dev-&gt;ip6_ptr under RCU and then unconditionally
increments its refcount. Device teardown can clear the pointer and drop
the last reference between these operations. The increment then
resurrects an object whose RCU free has already been queued, so callers
can use it after it is freed.

Use refcount_inc_not_zero() and return NULL when the object has already
reached zero. RCU keeps the memory accessible through the attempted
reference acquisition, and a successful increment pins the object for
the caller.

An independent run on the exact unpatched 6f5156d7a31a (v7.2-rc3)
kernel reproduced the invalid reference acquisition as UID 1000:

  refcount_t: addition on 0; use-after-free.
  ip6_mc_source+0xef4/0x17e0

It was followed by the corresponding reference underflow in
ip6_mc_source(). The supplied trace from the same unpatched revision
additionally shows the access after the RCU read-side section ends:

  BUG: KASAN: slab-use-after-free in mutex_lock+0x76/0xe0
  Write of size 8 at addr ffff888015b50240 by task poc/1219

Bug found and triaged by OpenAI Security Research and
validated by Trail of Bits.

Fixes: 8814c4b53381 ("[IPV6] ADDRCONF: Convert addrconf_lock to RCU.")
Cc: stable@vger.kernel.org
Signed-off-by: Kyle Zeng &lt;kylebot@openai.com&gt;
Co-developed-by: David Lee &lt;david.lee@trailofbits.com&gt;
Signed-off-by: David Lee &lt;david.lee@trailofbits.com&gt;
Reviewed-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Link: https://patch.msgid.link/20260803122758.666112-1-david.lee@trailofbits.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
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