linux-stable.git/include, branch v6.1.187 Linux kernel stable tree Bluetooth: hci_core: Fix hci_conn_hash_lookup_cis 2026-09-02T12:28:36+00:00 Luiz Augusto von Dentz luiz.von.dentz@intel.com 2023-12-08T22:22:29+00:00 ebf6edaf487143e9793b5370f6c3c7e1741f7046 commit 50efc63d1a7a7b9a6ed21adae1b9a7123ec8abc0 upstream. hci_conn_hash_lookup_cis shall always match the requested CIG and CIS ids even when they are unset as otherwise it result in not being able to bind/connect different sockets to the same address as that would result in having multiple sockets mapping to the same hci_conn which doesn't really work and prevents BAP audio configuration such as AC 6(i) when CIG and CIS are left unset. Fixes: c14516faede3 ("Bluetooth: hci_conn: Fix not matching by CIS ID") Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 50efc63d1a7a7b9a6ed21adae1b9a7123ec8abc0 upstream.

hci_conn_hash_lookup_cis shall always match the requested CIG and CIS
ids even when they are unset as otherwise it result in not being able
to bind/connect different sockets to the same address as that would
result in having multiple sockets mapping to the same hci_conn which
doesn't really work and prevents BAP audio configuration such as
AC 6(i) when CIG and CIS are left unset.

Fixes: c14516faede3 ("Bluetooth: hci_conn: Fix not matching by CIS ID")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
usb: gadget: f_tcm: keep port count until LUN teardown completes 2026-09-02T12:28:35+00:00 Shuangpeng Bai shuangpeng.kernel@gmail.com 2026-08-07T06:07:33+00:00 178f59a0bccd3f66cdfa5184310f31a58b7257c4 commit c39d0916da47d94909391876c9e5bd429ea7b1b9 upstream. tcm_usbg_drop_nexus() permits session removal once tpg_port_count reaches zero. However, usbg_port_unlink() currently decrements that count from the fabric_pre_unlink() callback, before core_dev_del_lun() waits for active se_lun references to drain. If removal of the last LUN races a nexus removal, the latter can observe a zero port count and call target_remove_session(). This frees sess_cmd_map while an in-flight struct usbg_cmd, including its work item, can still be accessed. Overlapping the last-LUN unlink with nexus removal reproduces this lifetime violation as a DEBUG_OBJECTS "free active" warning for usbg_cmd_work, followed by a target-core BUG/Oops. The generic target-core unlink path has no callback after core_dev_del_lun() completes. Add an optional fabric_post_unlink() callback and use it for the f_tcm port count. The count now remains nonzero until core_dev_del_lun() has finished draining active LUN references, preventing nexus removal from freeing the session during command completion. Fixes: c52661d60f63 ("usb-gadget: Initial merge of target module for UASP + BOT") Cc: stable@vger.kernel.org Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com> Link: https://patch.msgid.link/20260807060733.3186624-1-shuangpeng.kernel@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c39d0916da47d94909391876c9e5bd429ea7b1b9 upstream.

tcm_usbg_drop_nexus() permits session removal once tpg_port_count
reaches zero. However, usbg_port_unlink() currently decrements that
count from the fabric_pre_unlink() callback, before core_dev_del_lun()
waits for active se_lun references to drain.

If removal of the last LUN races a nexus removal, the latter can observe
a zero port count and call target_remove_session(). This frees
sess_cmd_map while an in-flight struct usbg_cmd, including its work item,
can still be accessed.

Overlapping the last-LUN unlink with nexus removal reproduces this
lifetime violation as a DEBUG_OBJECTS "free active" warning for
usbg_cmd_work, followed by a target-core BUG/Oops.

The generic target-core unlink path has no callback after
core_dev_del_lun() completes. Add an optional fabric_post_unlink()
callback and use it for the f_tcm port count. The count now remains
nonzero until core_dev_del_lun() has finished draining active LUN
references, preventing nexus removal from freeing the session during
command completion.

Fixes: c52661d60f63 ("usb-gadget: Initial merge of target module for UASP + BOT")
Cc: stable@vger.kernel.org
Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Link: https://patch.msgid.link/20260807060733.3186624-1-shuangpeng.kernel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ipv4: igmp: Fix potential UAF in igmp_gq_start_timer() 2026-09-02T12:28:34+00:00 Eric Dumazet edumazet@google.com 2026-07-05T18:17:54+00:00 74b301f7f197517016befb5f5dfab01f7bc64be5 commit 7b19c0f81ed1fdaec6bc522569be367199a9edf3 upstream. A race condition exists between device teardown (inetdev_destroy) and incoming IGMP query processing (igmp_rcv), leading to a Use-After-Free in the IGMP timer callback. During device destruction, inetdev_destroy() drops the primary reference to in_device, which can drop its refcount to 0. The actual freeing of in_device memory is deferred via RCU (using call_rcu()). Concurrently, igmp_rcv() runs under RCU read lock and obtains the in_device pointer. Because the memory is RCU-protected, CPU-0 can safely dereference in_device even if its refcount has hit 0. However, if CPU-0 calls igmp_gq_start_timer() and re-arms the timer, it attempts to acquire a reference using in_dev_hold(). This increments the refcount from 0 to 1, triggering a "refcount_t: addition on 0" warning. Since the in_device memory is still scheduled to be freed after the RCU grace period (as the free callback does not check the refcount again), the device is freed while the timer is still armed. When the timer expires, it accesses the freed memory, causing a kernel panic. Fix this by using refcount_inc_not_zero() (via a new helper in_dev_hold_safe()) to prevent acquiring a reference if the device is already being destroyed. If the refcount is 0, we do not arm the timer. A similar issue in IPv6 MLD is fixed in a subsequent patch. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Zero Day Initiative <zdi-disclosures@trendmicro.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Link: https://patch.msgid.link/20260705181756.963063-2-edumazet@google.com Signed-off-by: Paolo Abeni <pabeni@redhat.com> [Denis Arefev: adapted for 6.1: keep prandom_u32_max(), get_random_u32_below() not used here] Signed-off-by: Denis Arefev <arefev@swemel.ru> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 7b19c0f81ed1fdaec6bc522569be367199a9edf3 upstream.

A race condition exists between device teardown (inetdev_destroy) and
incoming IGMP query processing (igmp_rcv), leading to a Use-After-Free
in the IGMP timer callback.

During device destruction, inetdev_destroy() drops the primary reference
to in_device, which can drop its refcount to 0. The actual freeing of
in_device memory is deferred via RCU (using call_rcu()).

Concurrently, igmp_rcv() runs under RCU read lock and obtains the
in_device pointer. Because the memory is RCU-protected, CPU-0 can safely
dereference in_device even if its refcount has hit 0.

However, if CPU-0 calls igmp_gq_start_timer() and re-arms the timer, it
attempts to acquire a reference using in_dev_hold(). This increments the
refcount from 0 to 1, triggering a "refcount_t: addition on 0" warning.
Since the in_device memory is still scheduled to be freed after the RCU
grace period (as the free callback does not check the refcount again),
the device is freed while the timer is still armed. When the timer
expires, it accesses the freed memory, causing a kernel panic.

Fix this by using refcount_inc_not_zero() (via a new helper
in_dev_hold_safe()) to prevent acquiring a reference if the device is
already being destroyed. If the refcount is 0, we do not arm the timer.

A similar issue in IPv6 MLD is fixed in a subsequent patch.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Zero Day Initiative <zdi-disclosures@trendmicro.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260705181756.963063-2-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
[Denis Arefev: adapted for 6.1: keep prandom_u32_max(),
get_random_u32_below() not used here]
Signed-off-by: Denis Arefev <arefev@swemel.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Bluetooth: ISO: use correct CIS order in Set CIG Parameters event 2026-09-02T12:28:34+00:00 Pauli Virtanen pav@iki.fi 2026-08-26T18:48:31+00:00 a35c0b5a965d24b37e0a2d87f6b39fa183f3b722 [ Upstream commit 71e9588435c38112d6a8686d3d8e7cc1de8fe22c ] The order of CIS handle array in Set CIG Parameters response shall match the order of the CIS_ID array in the command (Core v5.3 Vol 4 Part E Sec 7.8.97). We send CIS_IDs mainly in the order of increasing CIS_ID (but with "last" CIS first if it has fixed CIG_ID). In handling of the reply, we currently assume this is also the same as the order of hci_conn in hdev->conn_hash, but that is not true. Match the correct hci_conn to the correct handle by matching them based on the CIG+CIS combination. The CIG+CIS combination shall be unique for ISO_LINK hci_conn at state >= BT_BOUND, which we maintain in hci_le_set_cig_params. Fixes: 26afbd826ee3 ("Bluetooth: Add initial implementation of CIS connections") Signed-off-by: Pauli Virtanen <pav@iki.fi> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Stable-dep-of: 0acd4eeb4b22 ("Bluetooth: hci_event: validate LE Set CIG Parameters response") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 71e9588435c38112d6a8686d3d8e7cc1de8fe22c ]

The order of CIS handle array in Set CIG Parameters response shall match
the order of the CIS_ID array in the command (Core v5.3 Vol 4 Part E Sec
7.8.97).  We send CIS_IDs mainly in the order of increasing CIS_ID (but
with "last" CIS first if it has fixed CIG_ID).  In handling of the
reply, we currently assume this is also the same as the order of
hci_conn in hdev->conn_hash, but that is not true.

Match the correct hci_conn to the correct handle by matching them based
on the CIG+CIS combination.  The CIG+CIS combination shall be unique for
ISO_LINK hci_conn at state >= BT_BOUND, which we maintain in
hci_le_set_cig_params.

Fixes: 26afbd826ee3 ("Bluetooth: Add initial implementation of CIS connections")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Stable-dep-of: 0acd4eeb4b22 ("Bluetooth: hci_event: validate LE Set CIG Parameters response")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Bluetooth: hci_conn: Fix not matching by CIS ID 2026-09-02T12:28:34+00:00 Luiz Augusto von Dentz luiz.von.dentz@intel.com 2026-08-26T18:48:30+00:00 ac1a7c3deb7f52694503f9d1c1c968a79f34a7ff [ Upstream commit c14516faede33c2c31da45cf950d55dbff42962e ] This fixes only matching CIS by address which prevents creating new hcon if upper layer is requesting a specific CIS ID. Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Stable-dep-of: 0acd4eeb4b22 ("Bluetooth: hci_event: validate LE Set CIG Parameters response") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit c14516faede33c2c31da45cf950d55dbff42962e ]

This fixes only matching CIS by address which prevents creating new hcon
if upper layer is requesting a specific CIS ID.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Stable-dep-of: 0acd4eeb4b22 ("Bluetooth: hci_event: validate LE Set CIG Parameters response")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
nvme: rename CDR/MORE/DNR to NVME_STATUS_* 2026-09-02T12:28:33+00:00 Weiwen Hu huweiwen@linux.alibaba.com 2026-08-26T14:54:00+00:00 978df308a2b1ef8d66ccac87197bd1319a0f426e [ Upstream commit dd0b0a4a2c5d7209457dc172997d1243ad269cfa ] CDR/MORE/DNR fields are not belonging to SC in the NVMe spec, rename them to NVME_STATUS_* to avoid confusion. Signed-off-by: Weiwen Hu <huweiwen@linux.alibaba.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Keith Busch <kbusch@kernel.org> Stable-dep-of: 4a3f00262a04 ("nvmet-tcp: bound SGL data length before allocating command buffers") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit dd0b0a4a2c5d7209457dc172997d1243ad269cfa ]

CDR/MORE/DNR fields are not belonging to SC in the NVMe spec, rename
them to NVME_STATUS_* to avoid confusion.

Signed-off-by: Weiwen Hu <huweiwen@linux.alibaba.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Stable-dep-of: 4a3f00262a04 ("nvmet-tcp: bound SGL data length before allocating command buffers")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
can: use skb hash instead of private variable in headroom 2026-08-27T12:29:05+00:00 Oliver Hartkopp socketcan@hartkopp.net 2026-08-25T12:27:14+00:00 cadee54a8691e40bf04f2ac4a108b413b8c88ef8 commit d4fb6514ff8ed6912a71294e6b66a5d59ee88007 upstream. The can_skb_priv::skbcnt variable is used to identify CAN skbs in the RX path analogue to the skb->hash. As the skb hash is not filled in CAN skbs move the private skbcnt value to skb->hash and set skb->sw_hash accordingly. The skb->hash is a value used for RPS to identify skbs. Use it as intended. Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Link: https://patch.msgid.link/20260201-can_skb_ext-v8-1-3635d790fe8b@hartkopp.net Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d4fb6514ff8ed6912a71294e6b66a5d59ee88007 upstream.

The can_skb_priv::skbcnt variable is used to identify CAN skbs in the RX
path analogue to the skb->hash.

As the skb hash is not filled in CAN skbs move the private skbcnt value to
skb->hash and set skb->sw_hash accordingly. The skb->hash is a value used
for RPS to identify skbs. Use it as intended.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20260201-can_skb_ext-v8-1-3635d790fe8b@hartkopp.net
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tls: fix lockless read of strp->msg_ready in ->poll 2026-08-27T12:29:03+00:00 Sabrina Dubroca sd@queasysnail.net 2024-04-24T10:25:47+00:00 6509e270ae1b4366a95f8d75b0dafec7b6f9e7a8 commit 0844370f8945086eb9335739d10205dcea8d707b upstream. tls_sk_poll is called without locking the socket, and needs to read strp->msg_ready (via tls_strp_msg_ready). Convert msg_ready to a bool and use READ_ONCE/WRITE_ONCE where needed. The remaining reads are only performed when the socket is locked. Fixes: 121dca784fc0 ("tls: suppress wakeups unless we have a full record") Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> Link: https://lore.kernel.org/r/0b7ee062319037cf86af6b317b3d72f7bfcd2e97.1713797701.git.sd@queasysnail.net Signed-off-by: Jakub Kicinski <kuba@kernel.org> Stable-dep-of: 0844370f8945 ("tls: fix lockless read of strp->msg_ready in ->poll") Assisted-by: Codex:GPT-5 Signed-off-by: Artem Dinaburg <artem@trailofbits.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 0844370f8945086eb9335739d10205dcea8d707b upstream.

tls_sk_poll is called without locking the socket, and needs to read
strp->msg_ready (via tls_strp_msg_ready). Convert msg_ready to a bool
and use READ_ONCE/WRITE_ONCE where needed. The remaining reads are
only performed when the socket is locked.

Fixes: 121dca784fc0 ("tls: suppress wakeups unless we have a full record")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://lore.kernel.org/r/0b7ee062319037cf86af6b317b3d72f7bfcd2e97.1713797701.git.sd@queasysnail.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 0844370f8945 ("tls: fix lockless read of strp->msg_ready in ->poll")
Assisted-by: Codex:GPT-5
Signed-off-by: Artem Dinaburg <artem@trailofbits.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
packet: use consistent hard_header_len in non-ring send paths 2026-08-27T12:29:02+00:00 Qihang Tang q.h.hack.winter@gmail.com 2026-08-21T11:00:16+00:00 142e287b3a25cfe909215177c23243e7fc5ae2b1 [ Upstream commit 03390aa32e669cc4ecd7d34108e2e1afc13d689d ] packet_snd() reads dev->hard_header_len multiple times while allocating and constructing an skb. Device reconfiguration can change this value concurrently, for example through bonding device type changes. For SOCK_RAW, packet_snd() can save a larger value in reserve and later allocate headroom using a smaller value. Moving skb->data back by reserve then places it before skb->head, and the following copy from userspace can attempt an out-of-bounds write. packet_sendmsg_spkt() has the same issue because it calculates its reservation and header offset from separate reads before dropping the RCU read lock to allocate the skb. Add LL_RESERVED_SPACE_EX() for callers that already saved a header length. Read hard_header_len once in packet_snd() and use it for allocation and construction. In packet_sendmsg_spkt(), preserve the allocation-time value through the device lookup retry. The separate SOCK_DGRAM consistency problem between hard_header_len and header_ops->create is not addressed here. Fixes: b84bbaf7a6c8 ("packet: in packet_snd start writing at link layer allocation") Cc: stable@vger.kernel.org Signed-off-by: Qihang Tang <q.h.hack.winter@gmail.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Link: https://patch.msgid.link/20260805125729.19220-3-q.h.hack.winter@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Stable-dep-of: 21b5953e7494 ("packet: use consistent hard_header_len in TX_RING send path") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 03390aa32e669cc4ecd7d34108e2e1afc13d689d ]

packet_snd() reads dev->hard_header_len multiple times while allocating
and constructing an skb. Device reconfiguration can change this value
concurrently, for example through bonding device type changes.

For SOCK_RAW, packet_snd() can save a larger value in reserve and later
allocate headroom using a smaller value. Moving skb->data back by reserve
then places it before skb->head, and the following copy from userspace can
attempt an out-of-bounds write.

packet_sendmsg_spkt() has the same issue because it calculates its
reservation and header offset from separate reads before dropping the RCU
read lock to allocate the skb.

Add LL_RESERVED_SPACE_EX() for callers that already saved a header length.
Read hard_header_len once in packet_snd() and use it for allocation and
construction. In packet_sendmsg_spkt(), preserve the allocation-time value
through the device lookup retry.

The separate SOCK_DGRAM consistency problem between hard_header_len and
header_ops->create is not addressed here.

Fixes: b84bbaf7a6c8 ("packet: in packet_snd start writing at link layer allocation")
Cc: stable@vger.kernel.org
Signed-off-by: Qihang Tang <q.h.hack.winter@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260805125729.19220-3-q.h.hack.winter@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 21b5953e7494 ("packet: use consistent hard_header_len in TX_RING send path")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kcov: fix data corruption and race conditions on PREEMPT_RT 2026-08-27T12:29:01+00:00 Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp 2026-07-15T23:01:29+00:00 5dc59fc959b2b5742985d7ef24bccd1868217dc2 commit 2eed77fdcb0cc48e8eccb2bcd4b7f2c6d650e84c upstream. syzbot is reporting KCOV state corruption on PREEMPT_RT kernels, for the temporary storage used for saving/restoring remote KCOV state is currently allocated as the per-CPU area. On PREEMPT_RT kernels, softirq handlers run as preemptible task threads (e.g., ksoftirqd). If a softirq context preempts a task running a remote KCOV session, it safely saves the task's state into the per-CPU area. However, if that softirq thread is subsequently preempted by a higher- priority softirq thread on the same CPU, the second softirq will overwrite the same per-CPU area, permanently destroying the original task's KCOV state. Fix this data corruption by moving the temporary storage from the per-CPU area to the per-thread area. Since each softirq thread now owns its own task context, nested softirq preemption no longer causes data overwrites. Note that while the temporary storage is now on a per-thread basis, the per-CPU kcov_percpu_data.lock must be retained, for we need to ensure that kcov_remote_start() and kcov_remote_stop() operate atomically without racing against asynchronous interrupts that manipulate the current task's KCOV state. It is likely that GFP_KERNEL allocation by vmalloc_node() in kcov_init() has already called panic() before returning NULL, for there will be no OOM-killable userspace processes when __init function of built-in module runs. But this patch also fixes crashing the kernel when vmalloc_node() in kcov_init() returned NULL, for kcov_init() left per-CPU irq_area == NULL but kcov_remote_start() depends on per-CPU irq_area != NULL, resulting in (1) doing vmalloc() in kcov_remote_start() despite !in_task() context (2) out-of-array-bounds access if (1) succeeded but kcov->remote_size < CONFIG_KCOV_IRQ_AREA_SIZE (3) always leak memory allocated by (1), eventually killing all OOM-killable userspace processes problems. Link: https://lore.kernel.org/43552d09-2ce2-4b19-b0d3-a2d1ab952145@I-love.SAKURA.ne.jp Reported-by: syzbot+3f51ad7ac3ae57a6fdcc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3f51ad7ac3ae57a6fdcc Reported-by: syzbot+47cf95ca1f9dcca872c8@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=47cf95ca1f9dcca872c8 Reported-by: syzbot+8a173e13208949931dc7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=8a173e13208949931dc7 Reported-by: syzbot+90984d3713722683112e@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=90984d3713722683112e Analyzed-by: AI Mode in Google Search (no mail address) Fixes: 5ff3b30ab57d ("kcov: collect coverage from interrupts") Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reviewed-by: Alexander Potapenko <glider@google.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Clark Williams <williams@redhat.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Marco Elver <elver@google.com> Cc: Mark Brown <broonie@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 2eed77fdcb0cc48e8eccb2bcd4b7f2c6d650e84c upstream.

syzbot is reporting KCOV state corruption on PREEMPT_RT kernels, for the
temporary storage used for saving/restoring remote KCOV state is currently
allocated as the per-CPU area.

On PREEMPT_RT kernels, softirq handlers run as preemptible task threads
(e.g., ksoftirqd). If a softirq context preempts a task running a remote
KCOV session, it safely saves the task's state into the per-CPU area.
However, if that softirq thread is subsequently preempted by a higher-
priority softirq thread on the same CPU, the second softirq will overwrite
the same per-CPU area, permanently destroying the original task's KCOV
state.

Fix this data corruption by moving the temporary storage from the per-CPU
area to the per-thread area. Since each softirq thread now owns its own
task context, nested softirq preemption no longer causes data overwrites.

Note that while the temporary storage is now on a per-thread basis, the
per-CPU kcov_percpu_data.lock must be retained, for we need to ensure that
kcov_remote_start() and kcov_remote_stop() operate atomically without
racing against asynchronous interrupts that manipulate the current task's
KCOV state.

It is likely that GFP_KERNEL allocation by vmalloc_node() in kcov_init()
has already called panic() before returning NULL, for there will be no
OOM-killable userspace processes when __init function of built-in module
runs. But this patch also fixes crashing the kernel when vmalloc_node()
in kcov_init() returned NULL, for kcov_init() left per-CPU irq_area == NULL
but kcov_remote_start() depends on per-CPU irq_area != NULL, resulting in

  (1) doing vmalloc() in kcov_remote_start() despite !in_task() context

  (2) out-of-array-bounds access if (1) succeeded but
      kcov->remote_size < CONFIG_KCOV_IRQ_AREA_SIZE

  (3) always leak memory allocated by (1), eventually killing all
      OOM-killable userspace processes

problems.

Link: https://lore.kernel.org/43552d09-2ce2-4b19-b0d3-a2d1ab952145@I-love.SAKURA.ne.jp
Reported-by: syzbot+3f51ad7ac3ae57a6fdcc@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=3f51ad7ac3ae57a6fdcc
Reported-by: syzbot+47cf95ca1f9dcca872c8@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=47cf95ca1f9dcca872c8
Reported-by: syzbot+8a173e13208949931dc7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8a173e13208949931dc7
Reported-by: syzbot+90984d3713722683112e@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=90984d3713722683112e
Analyzed-by: AI Mode in Google Search (no mail address)
Fixes: 5ff3b30ab57d ("kcov: collect coverage from interrupts")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Marco Elver <elver@google.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>