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Message-ID: <2025022754-CVE-2025-21812-9b17@gregkh>
Date: Thu, 27 Feb 2025 12:00:06 -0800
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21812: ax25: rcu protect dev->ax25_ptr
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
ax25: rcu protect dev->ax25_ptr
syzbot found a lockdep issue [1].
We should remove ax25 RTNL dependency in ax25_setsockopt()
This should also fix a variety of possible UAF in ax25.
[1]
WARNING: possible circular locking dependency detected
6.13.0-rc3-syzkaller-00762-g9268abe611b0 #0 Not tainted
------------------------------------------------------
syz.5.1818/12806 is trying to acquire lock:
ffffffff8fcb3988 (rtnl_mutex){+.+.}-{4:4}, at: ax25_setsockopt+0xa55/0xe90 net/ax25/af_ax25.c:680
but task is already holding lock:
ffff8880617ac258 (sk_lock-AF_AX25){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1618 [inline]
ffff8880617ac258 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_setsockopt+0x209/0xe90 net/ax25/af_ax25.c:574
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (sk_lock-AF_AX25){+.+.}-{0:0}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
lock_sock_nested+0x48/0x100 net/core/sock.c:3642
lock_sock include/net/sock.h:1618 [inline]
ax25_kill_by_device net/ax25/af_ax25.c:101 [inline]
ax25_device_event+0x24d/0x580 net/ax25/af_ax25.c:146
notifier_call_chain+0x1a5/0x3f0 kernel/notifier.c:85
__dev_notify_flags+0x207/0x400
dev_change_flags+0xf0/0x1a0 net/core/dev.c:9026
dev_ifsioc+0x7c8/0xe70 net/core/dev_ioctl.c:563
dev_ioctl+0x719/0x1340 net/core/dev_ioctl.c:820
sock_do_ioctl+0x240/0x460 net/socket.c:1234
sock_ioctl+0x626/0x8e0 net/socket.c:1339
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (rtnl_mutex){+.+.}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
__lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
__mutex_lock_common kernel/locking/mutex.c:585 [inline]
__mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
ax25_setsockopt+0xa55/0xe90 net/ax25/af_ax25.c:680
do_sock_setsockopt+0x3af/0x720 net/socket.c:2324
__sys_setsockopt net/socket.c:2349 [inline]
__do_sys_setsockopt net/socket.c:2355 [inline]
__se_sys_setsockopt net/socket.c:2352 [inline]
__x64_sys_setsockopt+0x1ee/0x280 net/socket.c:2352
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(sk_lock-AF_AX25);
lock(rtnl_mutex);
lock(sk_lock-AF_AX25);
lock(rtnl_mutex);
*** DEADLOCK ***
1 lock held by syz.5.1818/12806:
#0: ffff8880617ac258 (sk_lock-AF_AX25){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1618 [inline]
#0: ffff8880617ac258 (sk_lock-AF_AX25){+.+.}-{0:0}, at: ax25_setsockopt+0x209/0xe90 net/ax25/af_ax25.c:574
stack backtrace:
CPU: 1 UID: 0 PID: 12806 Comm: syz.5.1818 Not tainted 6.13.0-rc3-syzkaller-00762-g9268abe611b0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
__lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
__mutex_lock_common kernel/locking/mutex.c:585 [inline]
__mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
ax25_setsockopt+0xa55/0xe90 net/ax25/af_ax25.c:680
do_sock_setsockopt+0x3af/0x720 net/socket.c:2324
__sys_setsockopt net/socket.c:2349 [inline]
__do_sys_setsockopt net/socket.c:2355 [inline]
__se_sys_setsockopt net/socket.c:2352 [inline]
__x64_sys_setsockopt+0x1ee/0x280 net/socket.c:2352
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7b62385d29
The Linux kernel CVE team has assigned CVE-2025-21812 to this issue.
Affected and fixed versions
===========================
Issue introduced in 5.0 with commit c433570458e49bccea5c551df628d058b3526289 and fixed in 6.1.129 with commit 2802ed4ced27ebd474828fc67ffd7d66f11e3605
Issue introduced in 5.0 with commit c433570458e49bccea5c551df628d058b3526289 and fixed in 6.6.76 with commit 7705d8a7f2c26c80973c81093db07c6022b2b30e
Issue introduced in 5.0 with commit c433570458e49bccea5c551df628d058b3526289 and fixed in 6.12.13 with commit 8937f5e38a218531dce2a89fae60e3adcc2311e1
Issue introduced in 5.0 with commit c433570458e49bccea5c551df628d058b3526289 and fixed in 6.13.2 with commit c2531db6de3c95551be58878f859c6a053b7eb2e
Issue introduced in 5.0 with commit c433570458e49bccea5c551df628d058b3526289 and fixed in 6.14-rc1 with commit 95fc45d1dea8e1253f8ec58abc5befb71553d666
Issue introduced in 3.18.132 with commit 7f93d703e276311dd289c9a520ce9e8c8fa2858c
Issue introduced in 4.4.170 with commit c0e93a6d36135d5082cb3af8352f5b69c9f58d6e
Issue introduced in 4.9.149 with commit c39b8fd4997bf99503b8e48d8cb0eedb1d9a54f0
Issue introduced in 4.14.92 with commit 26a5adc8eb26d170058645c3cccd4d19165bec16
Issue introduced in 4.19.14 with commit 3e881d8764ed9b04ae3e5c3e5d132acb75ef91ba
Issue introduced in 4.20.1 with commit 77768c96dcf860c43b970b87b2a09229f84ea560
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2025-21812
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
include/linux/netdevice.h
include/net/ax25.h
net/ax25/af_ax25.c
net/ax25/ax25_dev.c
net/ax25/ax25_ip.c
net/ax25/ax25_out.c
net/ax25/ax25_route.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/2802ed4ced27ebd474828fc67ffd7d66f11e3605
https://git.kernel.org/stable/c/7705d8a7f2c26c80973c81093db07c6022b2b30e
https://git.kernel.org/stable/c/8937f5e38a218531dce2a89fae60e3adcc2311e1
https://git.kernel.org/stable/c/c2531db6de3c95551be58878f859c6a053b7eb2e
https://git.kernel.org/stable/c/95fc45d1dea8e1253f8ec58abc5befb71553d666
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