<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/include/net/addrconf.h, branch linux-rolling-lts</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>ipv6: mcast: Fix potential UAF in MLD delayed work</title>
<updated>2026-07-24T14:16:49+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2026-07-05T18:17:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9ce741c22df4fd9546e30306317ac7df3607e48f'/>
<id>9ce741c22df4fd9546e30306317ac7df3607e48f</id>
<content type='text'>
[ Upstream commit 9b26518b6896a16b809b1e42986f4ebac7bccc1e ]

A race condition exists between device teardown and incoming MLD query
processing, leading to a Use-After-Free in the MLD delayed work.

During device destruction, the primary reference to inet6_dev is dropped,
which can drop its refcount to 0. The actual freeing of inet6_dev memory
is deferred via RCU.

Concurrently, the packet receive path runs under RCU read lock and obtains
the inet6_dev pointer. Because the memory is RCU-protected, CPU-0 can
safely dereference inet6_dev even if its refcount has hit 0.

However, if CPU-0 calls igmp6_event_query() and schedules delayed work, it
attempts to acquire a reference using in6_dev_hold(). This increments the
refcount from 0 to 1, triggering a "refcount_t: addition on 0" warning.
Since the inet6_dev memory is still scheduled to be freed after the RCU
grace period, the device is freed while the work is still scheduled.
When the work runs, it accesses the freed memory, causing a kernel panic.

Fix this by using refcount_inc_not_zero() (via a new helper
in6_dev_hold_safe()) to prevent acquiring a reference if the device is
already being destroyed. If the refcount is 0, we do not schedule the work.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reviewed-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Link: https://patch.msgid.link/20260705181756.963063-3-edumazet@google.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
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 9b26518b6896a16b809b1e42986f4ebac7bccc1e ]

A race condition exists between device teardown and incoming MLD query
processing, leading to a Use-After-Free in the MLD delayed work.

During device destruction, the primary reference to inet6_dev is dropped,
which can drop its refcount to 0. The actual freeing of inet6_dev memory
is deferred via RCU.

Concurrently, the packet receive path runs under RCU read lock and obtains
the inet6_dev pointer. Because the memory is RCU-protected, CPU-0 can
safely dereference inet6_dev even if its refcount has hit 0.

However, if CPU-0 calls igmp6_event_query() and schedules delayed work, it
attempts to acquire a reference using in6_dev_hold(). This increments the
refcount from 0 to 1, triggering a "refcount_t: addition on 0" warning.
Since the inet6_dev memory is still scheduled to be freed after the RCU
grace period, the device is freed while the work is still scheduled.
When the work runs, it accesses the freed memory, causing a kernel panic.

Fix this by using refcount_inc_not_zero() (via a new helper
in6_dev_hold_safe()) to prevent acquiring a reference if the device is
already being destroyed. If the refcount is 0, we do not schedule the work.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reviewed-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Link: https://patch.msgid.link/20260705181756.963063-3-edumazet@google.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ipv6: guard against possible NULL deref in __in6_dev_stats_get()</title>
<updated>2026-07-24T14:15:54+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2026-05-26T14:55:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0db1949084e85a72d174a7dea3259b94fe5a9305'/>
<id>0db1949084e85a72d174a7dea3259b94fe5a9305</id>
<content type='text'>
[ Upstream commit 507541c2a8eeb76c02bd2511958f73a8cfa3e1bc ]

dev_get_by_index_rcu() could return NULL if the original physical
device is unregistered.

Found by Sashiko.

Fixes: e1ae5c2ea478 ("vrf: Increment Icmp6InMsgs on the original netdev")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Stephen Suryaputra &lt;ssuryaextr@gmail.com&gt;
Reviewed-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Link: https://patch.msgid.link/20260526145529.3587126-2-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
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 507541c2a8eeb76c02bd2511958f73a8cfa3e1bc ]

dev_get_by_index_rcu() could return NULL if the original physical
device is unregistered.

Found by Sashiko.

Fixes: e1ae5c2ea478 ("vrf: Increment Icmp6InMsgs on the original netdev")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Stephen Suryaputra &lt;ssuryaextr@gmail.com&gt;
Reviewed-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Link: https://patch.msgid.link/20260526145529.3587126-2-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ipv6: Add __in6_dev_get_rtnl_net().</title>
<updated>2025-01-20T20:16:04+00:00</updated>
<author>
<name>Kuniyuki Iwashima</name>
<email>kuniyu@amazon.com</email>
</author>
<published>2025-01-15T08:05:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f7a6082b5e4c15f34fd766cf0960f7e082009c54'/>
<id>f7a6082b5e4c15f34fd766cf0960f7e082009c54</id>
<content type='text'>
We will convert rtnl_lock() with rtnl_net_lock(), and we want to
convert __in6_dev_get() too.

__in6_dev_get() uses rcu_dereference_rtnl(), but as written in its
comment, rtnl_dereference() or rcu_dereference() is preferable.

Let's add __in6_dev_get_rtnl_net() that uses rtnl_net_dereference().

We can add the RCU version helper later if needed.

Signed-off-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Link: https://patch.msgid.link/20250115080608.28127-2-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We will convert rtnl_lock() with rtnl_net_lock(), and we want to
convert __in6_dev_get() too.

__in6_dev_get() uses rcu_dereference_rtnl(), but as written in its
comment, rtnl_dereference() or rcu_dereference() is preferable.

Let's add __in6_dev_get_rtnl_net() that uses rtnl_net_dereference().

We can add the RCU version helper later if needed.

Signed-off-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Link: https://patch.msgid.link/20250115080608.28127-2-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>netlink: add IPv6 anycast join/leave notifications</title>
<updated>2025-01-09T11:54:45+00:00</updated>
<author>
<name>Yuyang Huang</name>
<email>yuyanghuang@google.com</email>
</author>
<published>2025-01-07T11:43:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=33d97a07b3ae6fa713919de4e1864ca04fff8f80'/>
<id>33d97a07b3ae6fa713919de4e1864ca04fff8f80</id>
<content type='text'>
This change introduces a mechanism for notifying userspace
applications about changes to IPv6 anycast addresses via netlink. It
includes:

* Addition and deletion of IPv6 anycast addresses are reported using
  RTM_NEWANYCAST and RTM_DELANYCAST.
* A new netlink group (RTNLGRP_IPV6_ACADDR) for subscribing to these
  notifications.

This enables user space applications(e.g. ip monitor) to efficiently
track anycast addresses through netlink messages, improving metrics
collection and system monitoring. It also unlocks the potential for
advanced anycast management in user space, such as hardware offload
control and fine grained network control.

Cc: Maciej Żenczykowski &lt;maze@google.com&gt;
Cc: Lorenzo Colitti &lt;lorenzo@google.com&gt;
Signed-off-by: Yuyang Huang &lt;yuyanghuang@google.com&gt;
Reviewed-by: David Ahern &lt;dsahern@kernel.org&gt;
Link: https://patch.msgid.link/20250107114355.1766086-1-yuyanghuang@google.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This change introduces a mechanism for notifying userspace
applications about changes to IPv6 anycast addresses via netlink. It
includes:

* Addition and deletion of IPv6 anycast addresses are reported using
  RTM_NEWANYCAST and RTM_DELANYCAST.
* A new netlink group (RTNLGRP_IPV6_ACADDR) for subscribing to these
  notifications.

This enables user space applications(e.g. ip monitor) to efficiently
track anycast addresses through netlink messages, improving metrics
collection and system monitoring. It also unlocks the potential for
advanced anycast management in user space, such as hardware offload
control and fine grained network control.

Cc: Maciej Żenczykowski &lt;maze@google.com&gt;
Cc: Lorenzo Colitti &lt;lorenzo@google.com&gt;
Signed-off-by: Yuyang Huang &lt;yuyanghuang@google.com&gt;
Reviewed-by: David Ahern &lt;dsahern@kernel.org&gt;
Link: https://patch.msgid.link/20250107114355.1766086-1-yuyanghuang@google.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>netlink: add IGMP/MLD join/leave notifications</title>
<updated>2024-12-15T12:31:35+00:00</updated>
<author>
<name>Yuyang Huang</name>
<email>yuyanghuang@google.com</email>
</author>
<published>2024-12-11T08:22:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=2c2b61d2138f472e50b5531ec0cb4a1485837e21'/>
<id>2c2b61d2138f472e50b5531ec0cb4a1485837e21</id>
<content type='text'>
This change introduces netlink notifications for multicast address
changes. The following features are included:
* Addition and deletion of multicast addresses are reported using
  RTM_NEWMULTICAST and RTM_DELMULTICAST messages with AF_INET and
  AF_INET6.
* Two new notification groups: RTNLGRP_IPV4_MCADDR and
  RTNLGRP_IPV6_MCADDR are introduced for receiving these events.

This change allows user space applications (e.g., ip monitor) to
efficiently track multicast group memberships by listening for netlink
events. Previously, applications relied on inefficient polling of
procfs, introducing delays. With netlink notifications, applications
receive realtime updates on multicast group membership changes,
enabling more precise metrics collection and system monitoring. 

This change also unlocks the potential for implementing a wide range
of sophisticated multicast related features in user space by allowing
applications to combine kernel provided multicast address information
with user space data and communicate decisions back to the kernel for
more fine grained control. This mechanism can be used for various
purposes, including multicast filtering, IGMP/MLD offload, and
IGMP/MLD snooping.

Cc: Maciej Żenczykowski &lt;maze@google.com&gt;
Cc: Lorenzo Colitti &lt;lorenzo@google.com&gt;
Co-developed-by: Patrick Ruddy &lt;pruddy@vyatta.att-mail.com&gt;
Signed-off-by: Patrick Ruddy &lt;pruddy@vyatta.att-mail.com&gt;
Link: https://lore.kernel.org/r/20180906091056.21109-1-pruddy@vyatta.att-mail.com
Signed-off-by: Yuyang Huang &lt;yuyanghuang@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This change introduces netlink notifications for multicast address
changes. The following features are included:
* Addition and deletion of multicast addresses are reported using
  RTM_NEWMULTICAST and RTM_DELMULTICAST messages with AF_INET and
  AF_INET6.
* Two new notification groups: RTNLGRP_IPV4_MCADDR and
  RTNLGRP_IPV6_MCADDR are introduced for receiving these events.

This change allows user space applications (e.g., ip monitor) to
efficiently track multicast group memberships by listening for netlink
events. Previously, applications relied on inefficient polling of
procfs, introducing delays. With netlink notifications, applications
receive realtime updates on multicast group membership changes,
enabling more precise metrics collection and system monitoring. 

This change also unlocks the potential for implementing a wide range
of sophisticated multicast related features in user space by allowing
applications to combine kernel provided multicast address information
with user space data and communicate decisions back to the kernel for
more fine grained control. This mechanism can be used for various
purposes, including multicast filtering, IGMP/MLD offload, and
IGMP/MLD snooping.

Cc: Maciej Żenczykowski &lt;maze@google.com&gt;
Cc: Lorenzo Colitti &lt;lorenzo@google.com&gt;
Co-developed-by: Patrick Ruddy &lt;pruddy@vyatta.att-mail.com&gt;
Signed-off-by: Patrick Ruddy &lt;pruddy@vyatta.att-mail.com&gt;
Link: https://lore.kernel.org/r/20180906091056.21109-1-pruddy@vyatta.att-mail.com
Signed-off-by: Yuyang Huang &lt;yuyanghuang@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: Correct spelling in headers</title>
<updated>2024-08-26T16:37:23+00:00</updated>
<author>
<name>Simon Horman</name>
<email>horms@kernel.org</email>
</author>
<published>2024-08-22T12:57:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=70d0bb45fae87a3b08970a318e15f317446a1956'/>
<id>70d0bb45fae87a3b08970a318e15f317446a1956</id>
<content type='text'>
Correct spelling in Networking headers.
As reported by codespell.

Signed-off-by: Simon Horman &lt;horms@kernel.org&gt;
Link: https://patch.msgid.link/20240822-net-spell-v1-12-3a98971ce2d2@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Correct spelling in Networking headers.
As reported by codespell.

Signed-off-by: Simon Horman &lt;horms@kernel.org&gt;
Link: https://patch.msgid.link/20240822-net-spell-v1-12-3a98971ce2d2@kernel.org
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ip: Move INFINITY_LIFE_TIME to addrconf.h.</title>
<updated>2024-08-16T01:56:14+00:00</updated>
<author>
<name>Kuniyuki Iwashima</name>
<email>kuniyu@amazon.com</email>
</author>
<published>2024-08-09T23:54:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=de67763cbdbba8149eeb5d45ad0c6834f7c7b352'/>
<id>de67763cbdbba8149eeb5d45ad0c6834f7c7b352</id>
<content type='text'>
INFINITY_LIFE_TIME is the common value used in IPv4 and IPv6 but defined
in both .c files.

Also, 0xffffffff used in addrconf_timeout_fixup() is INFINITY_LIFE_TIME.

Let's move INFINITY_LIFE_TIME's definition to addrconf.h

Signed-off-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Link: https://patch.msgid.link/20240809235406.50187-6-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
INFINITY_LIFE_TIME is the common value used in IPv4 and IPv6 but defined
in both .c files.

Also, 0xffffffff used in addrconf_timeout_fixup() is INFINITY_LIFE_TIME.

Let's move INFINITY_LIFE_TIME's definition to addrconf.h

Signed-off-by: Kuniyuki Iwashima &lt;kuniyu@amazon.com&gt;
Link: https://patch.msgid.link/20240809235406.50187-6-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Add support for PIO p flag</title>
<updated>2024-07-31T12:49:48+00:00</updated>
<author>
<name>Patrick Rohr</name>
<email>prohr@google.com</email>
</author>
<published>2024-07-29T22:00:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=990c304930138dcd7a49763417e6e5313b81293e'/>
<id>990c304930138dcd7a49763417e6e5313b81293e</id>
<content type='text'>
draft-ietf-6man-pio-pflag is adding a new flag to the Prefix Information
Option to signal that the network can allocate a unique IPv6 prefix per
client via DHCPv6-PD (see draft-ietf-v6ops-dhcp-pd-per-device).

When ra_honor_pio_pflag is enabled, the presence of a P-flag causes
SLAAC autoconfiguration to be disabled for that particular PIO.

An automated test has been added in Android (r.android.com/3195335) to
go along with this change.

Cc: Maciej Żenczykowski &lt;maze@google.com&gt;
Cc: Lorenzo Colitti &lt;lorenzo@google.com&gt;
Cc: David Lamparter &lt;equinox@opensourcerouting.org&gt;
Cc: Simon Horman &lt;horms@kernel.org&gt;
Signed-off-by: Patrick Rohr &lt;prohr@google.com&gt;
Reviewed-by: Maciej Żenczykowski &lt;maze@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
draft-ietf-6man-pio-pflag is adding a new flag to the Prefix Information
Option to signal that the network can allocate a unique IPv6 prefix per
client via DHCPv6-PD (see draft-ietf-v6ops-dhcp-pd-per-device).

When ra_honor_pio_pflag is enabled, the presence of a P-flag causes
SLAAC autoconfiguration to be disabled for that particular PIO.

An automated test has been added in Android (r.android.com/3195335) to
go along with this change.

Cc: Maciej Żenczykowski &lt;maze@google.com&gt;
Cc: Lorenzo Colitti &lt;lorenzo@google.com&gt;
Cc: David Lamparter &lt;equinox@opensourcerouting.org&gt;
Cc: Simon Horman &lt;horms@kernel.org&gt;
Signed-off-by: Patrick Rohr &lt;prohr@google.com&gt;
Reviewed-by: Maciej Żenczykowski &lt;maze@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr</title>
<updated>2024-04-10T00:09:05+00:00</updated>
<author>
<name>Jiri Benc</name>
<email>jbenc@redhat.com</email>
</author>
<published>2024-04-08T14:18:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7633c4da919ad51164acbf1aa322cc1a3ead6129'/>
<id>7633c4da919ad51164acbf1aa322cc1a3ead6129</id>
<content type='text'>
Although ipv6_get_ifaddr walks inet6_addr_lst under the RCU lock, it
still means hlist_for_each_entry_rcu can return an item that got removed
from the list. The memory itself of such item is not freed thanks to RCU
but nothing guarantees the actual content of the memory is sane.

In particular, the reference count can be zero. This can happen if
ipv6_del_addr is called in parallel. ipv6_del_addr removes the entry
from inet6_addr_lst (hlist_del_init_rcu(&amp;ifp-&gt;addr_lst)) and drops all
references (__in6_ifa_put(ifp) + in6_ifa_put(ifp)). With bad enough
timing, this can happen:

1. In ipv6_get_ifaddr, hlist_for_each_entry_rcu returns an entry.

2. Then, the whole ipv6_del_addr is executed for the given entry. The
   reference count drops to zero and kfree_rcu is scheduled.

3. ipv6_get_ifaddr continues and tries to increments the reference count
   (in6_ifa_hold).

4. The rcu is unlocked and the entry is freed.

5. The freed entry is returned.

Prevent increasing of the reference count in such case. The name
in6_ifa_hold_safe is chosen to mimic the existing fib6_info_hold_safe.

[   41.506330] refcount_t: addition on 0; use-after-free.
[   41.506760] WARNING: CPU: 0 PID: 595 at lib/refcount.c:25 refcount_warn_saturate+0xa5/0x130
[   41.507413] Modules linked in: veth bridge stp llc
[   41.507821] CPU: 0 PID: 595 Comm: python3 Not tainted 6.9.0-rc2.main-00208-g49563be82afa #14
[   41.508479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
[   41.509163] RIP: 0010:refcount_warn_saturate+0xa5/0x130
[   41.509586] Code: ad ff 90 0f 0b 90 90 c3 cc cc cc cc 80 3d c0 30 ad 01 00 75 a0 c6 05 b7 30 ad 01 01 90 48 c7 c7 38 cc 7a 8c e8 cc 18 ad ff 90 &lt;0f&gt; 0b 90 90 c3 cc cc cc cc 80 3d 98 30 ad 01 00 0f 85 75 ff ff ff
[   41.510956] RSP: 0018:ffffbda3c026baf0 EFLAGS: 00010282
[   41.511368] RAX: 0000000000000000 RBX: ffff9e9c46914800 RCX: 0000000000000000
[   41.511910] RDX: ffff9e9c7ec29c00 RSI: ffff9e9c7ec1c900 RDI: ffff9e9c7ec1c900
[   41.512445] RBP: ffff9e9c43660c9c R08: 0000000000009ffb R09: 00000000ffffdfff
[   41.512998] R10: 00000000ffffdfff R11: ffffffff8ca58a40 R12: ffff9e9c4339a000
[   41.513534] R13: 0000000000000001 R14: ffff9e9c438a0000 R15: ffffbda3c026bb48
[   41.514086] FS:  00007fbc4cda1740(0000) GS:ffff9e9c7ec00000(0000) knlGS:0000000000000000
[   41.514726] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   41.515176] CR2: 000056233b337d88 CR3: 000000000376e006 CR4: 0000000000370ef0
[   41.515713] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   41.516252] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   41.516799] Call Trace:
[   41.517037]  &lt;TASK&gt;
[   41.517249]  ? __warn+0x7b/0x120
[   41.517535]  ? refcount_warn_saturate+0xa5/0x130
[   41.517923]  ? report_bug+0x164/0x190
[   41.518240]  ? handle_bug+0x3d/0x70
[   41.518541]  ? exc_invalid_op+0x17/0x70
[   41.520972]  ? asm_exc_invalid_op+0x1a/0x20
[   41.521325]  ? refcount_warn_saturate+0xa5/0x130
[   41.521708]  ipv6_get_ifaddr+0xda/0xe0
[   41.522035]  inet6_rtm_getaddr+0x342/0x3f0
[   41.522376]  ? __pfx_inet6_rtm_getaddr+0x10/0x10
[   41.522758]  rtnetlink_rcv_msg+0x334/0x3d0
[   41.523102]  ? netlink_unicast+0x30f/0x390
[   41.523445]  ? __pfx_rtnetlink_rcv_msg+0x10/0x10
[   41.523832]  netlink_rcv_skb+0x53/0x100
[   41.524157]  netlink_unicast+0x23b/0x390
[   41.524484]  netlink_sendmsg+0x1f2/0x440
[   41.524826]  __sys_sendto+0x1d8/0x1f0
[   41.525145]  __x64_sys_sendto+0x1f/0x30
[   41.525467]  do_syscall_64+0xa5/0x1b0
[   41.525794]  entry_SYSCALL_64_after_hwframe+0x72/0x7a
[   41.526213] RIP: 0033:0x7fbc4cfcea9a
[   41.526528] Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 &lt;48&gt; 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89
[   41.527942] RSP: 002b:00007ffcf54012a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
[   41.528593] RAX: ffffffffffffffda RBX: 00007ffcf5401368 RCX: 00007fbc4cfcea9a
[   41.529173] RDX: 000000000000002c RSI: 00007fbc4b9d9bd0 RDI: 0000000000000005
[   41.529786] RBP: 00007fbc4bafb040 R08: 00007ffcf54013e0 R09: 000000000000000c
[   41.530375] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[   41.530977] R13: ffffffffc4653600 R14: 0000000000000001 R15: 00007fbc4ca85d1b
[   41.531573]  &lt;/TASK&gt;

Fixes: 5c578aedcb21d ("IPv6: convert addrconf hash list to RCU")
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reviewed-by: David Ahern &lt;dsahern@kernel.org&gt;
Signed-off-by: Jiri Benc &lt;jbenc@redhat.com&gt;
Link: https://lore.kernel.org/r/8ab821e36073a4a406c50ec83c9e8dc586c539e4.1712585809.git.jbenc@redhat.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Although ipv6_get_ifaddr walks inet6_addr_lst under the RCU lock, it
still means hlist_for_each_entry_rcu can return an item that got removed
from the list. The memory itself of such item is not freed thanks to RCU
but nothing guarantees the actual content of the memory is sane.

In particular, the reference count can be zero. This can happen if
ipv6_del_addr is called in parallel. ipv6_del_addr removes the entry
from inet6_addr_lst (hlist_del_init_rcu(&amp;ifp-&gt;addr_lst)) and drops all
references (__in6_ifa_put(ifp) + in6_ifa_put(ifp)). With bad enough
timing, this can happen:

1. In ipv6_get_ifaddr, hlist_for_each_entry_rcu returns an entry.

2. Then, the whole ipv6_del_addr is executed for the given entry. The
   reference count drops to zero and kfree_rcu is scheduled.

3. ipv6_get_ifaddr continues and tries to increments the reference count
   (in6_ifa_hold).

4. The rcu is unlocked and the entry is freed.

5. The freed entry is returned.

Prevent increasing of the reference count in such case. The name
in6_ifa_hold_safe is chosen to mimic the existing fib6_info_hold_safe.

[   41.506330] refcount_t: addition on 0; use-after-free.
[   41.506760] WARNING: CPU: 0 PID: 595 at lib/refcount.c:25 refcount_warn_saturate+0xa5/0x130
[   41.507413] Modules linked in: veth bridge stp llc
[   41.507821] CPU: 0 PID: 595 Comm: python3 Not tainted 6.9.0-rc2.main-00208-g49563be82afa #14
[   41.508479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
[   41.509163] RIP: 0010:refcount_warn_saturate+0xa5/0x130
[   41.509586] Code: ad ff 90 0f 0b 90 90 c3 cc cc cc cc 80 3d c0 30 ad 01 00 75 a0 c6 05 b7 30 ad 01 01 90 48 c7 c7 38 cc 7a 8c e8 cc 18 ad ff 90 &lt;0f&gt; 0b 90 90 c3 cc cc cc cc 80 3d 98 30 ad 01 00 0f 85 75 ff ff ff
[   41.510956] RSP: 0018:ffffbda3c026baf0 EFLAGS: 00010282
[   41.511368] RAX: 0000000000000000 RBX: ffff9e9c46914800 RCX: 0000000000000000
[   41.511910] RDX: ffff9e9c7ec29c00 RSI: ffff9e9c7ec1c900 RDI: ffff9e9c7ec1c900
[   41.512445] RBP: ffff9e9c43660c9c R08: 0000000000009ffb R09: 00000000ffffdfff
[   41.512998] R10: 00000000ffffdfff R11: ffffffff8ca58a40 R12: ffff9e9c4339a000
[   41.513534] R13: 0000000000000001 R14: ffff9e9c438a0000 R15: ffffbda3c026bb48
[   41.514086] FS:  00007fbc4cda1740(0000) GS:ffff9e9c7ec00000(0000) knlGS:0000000000000000
[   41.514726] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   41.515176] CR2: 000056233b337d88 CR3: 000000000376e006 CR4: 0000000000370ef0
[   41.515713] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   41.516252] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   41.516799] Call Trace:
[   41.517037]  &lt;TASK&gt;
[   41.517249]  ? __warn+0x7b/0x120
[   41.517535]  ? refcount_warn_saturate+0xa5/0x130
[   41.517923]  ? report_bug+0x164/0x190
[   41.518240]  ? handle_bug+0x3d/0x70
[   41.518541]  ? exc_invalid_op+0x17/0x70
[   41.520972]  ? asm_exc_invalid_op+0x1a/0x20
[   41.521325]  ? refcount_warn_saturate+0xa5/0x130
[   41.521708]  ipv6_get_ifaddr+0xda/0xe0
[   41.522035]  inet6_rtm_getaddr+0x342/0x3f0
[   41.522376]  ? __pfx_inet6_rtm_getaddr+0x10/0x10
[   41.522758]  rtnetlink_rcv_msg+0x334/0x3d0
[   41.523102]  ? netlink_unicast+0x30f/0x390
[   41.523445]  ? __pfx_rtnetlink_rcv_msg+0x10/0x10
[   41.523832]  netlink_rcv_skb+0x53/0x100
[   41.524157]  netlink_unicast+0x23b/0x390
[   41.524484]  netlink_sendmsg+0x1f2/0x440
[   41.524826]  __sys_sendto+0x1d8/0x1f0
[   41.525145]  __x64_sys_sendto+0x1f/0x30
[   41.525467]  do_syscall_64+0xa5/0x1b0
[   41.525794]  entry_SYSCALL_64_after_hwframe+0x72/0x7a
[   41.526213] RIP: 0033:0x7fbc4cfcea9a
[   41.526528] Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 &lt;48&gt; 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89
[   41.527942] RSP: 002b:00007ffcf54012a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
[   41.528593] RAX: ffffffffffffffda RBX: 00007ffcf5401368 RCX: 00007fbc4cfcea9a
[   41.529173] RDX: 000000000000002c RSI: 00007fbc4b9d9bd0 RDI: 0000000000000005
[   41.529786] RBP: 00007fbc4bafb040 R08: 00007ffcf54013e0 R09: 000000000000000c
[   41.530375] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[   41.530977] R13: ffffffffc4653600 R14: 0000000000000001 R15: 00007fbc4ca85d1b
[   41.531573]  &lt;/TASK&gt;

Fixes: 5c578aedcb21d ("IPv6: convert addrconf hash list to RCU")
Reviewed-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reviewed-by: David Ahern &lt;dsahern@kernel.org&gt;
Signed-off-by: Jiri Benc &lt;jbenc@redhat.com&gt;
Link: https://lore.kernel.org/r/8ab821e36073a4a406c50ec83c9e8dc586c539e4.1712585809.git.jbenc@redhat.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ipv6: annotate data-races around idev-&gt;cnf.ignore_routes_with_linkdown</title>
<updated>2024-03-01T08:42:32+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2024-02-28T13:54:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fca34cc075996767fbbdb6252be9ddd21c34c920'/>
<id>fca34cc075996767fbbdb6252be9ddd21c34c920</id>
<content type='text'>
idev-&gt;cnf.ignore_routes_with_linkdown can be used without any locks,
add appropriate annotations.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reviewed-by: Jiri Pirko &lt;jiri@nvidia.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
idev-&gt;cnf.ignore_routes_with_linkdown can be used without any locks,
add appropriate annotations.

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reviewed-by: Jiri Pirko &lt;jiri@nvidia.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
</feed>
