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Message-ID: <2024102129-CVE-2024-49946-762f@gregkh>
Date: Mon, 21 Oct 2024 20:02:34 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-49946: ppp: do not assume bh is held in ppp_channel_bridge_input()
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
ppp: do not assume bh is held in ppp_channel_bridge_input()
Networking receive path is usually handled from BH handler.
However, some protocols need to acquire the socket lock, and
packets might be stored in the socket backlog is the socket was
owned by a user process.
In this case, release_sock(), __release_sock(), and sk_backlog_rcv()
might call the sk->sk_backlog_rcv() handler in process context.
sybot caught ppp was not considering this case in
ppp_channel_bridge_input() :
WARNING: inconsistent lock state
6.11.0-rc7-syzkaller-g5f5673607153 #0 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
ksoftirqd/1/24 [HC0[0]:SC1[1]:HE1:SE0] takes:
ffff0000db7f11e0 (&pch->downl){+.?.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff0000db7f11e0 (&pch->downl){+.?.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
ffff0000db7f11e0 (&pch->downl){+.?.}-{2:2}, at: ppp_input+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304
{SOFTIRQ-ON-W} state was registered at:
lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5759
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x48/0x60 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
ppp_input+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304
pppoe_rcv_core+0xfc/0x314 drivers/net/ppp/pppoe.c:379
sk_backlog_rcv include/net/sock.h:1111 [inline]
__release_sock+0x1a8/0x3d8 net/core/sock.c:3004
release_sock+0x68/0x1b8 net/core/sock.c:3558
pppoe_sendmsg+0xc8/0x5d8 drivers/net/ppp/pppoe.c:903
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
__sys_sendto+0x374/0x4f4 net/socket.c:2204
__do_sys_sendto net/socket.c:2216 [inline]
__se_sys_sendto net/socket.c:2212 [inline]
__arm64_sys_sendto+0xd8/0xf8 net/socket.c:2212
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
irq event stamp: 282914
hardirqs last enabled at (282914): [<ffff80008b42e30c>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
hardirqs last enabled at (282914): [<ffff80008b42e30c>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:194
hardirqs last disabled at (282913): [<ffff80008b42e13c>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline]
hardirqs last disabled at (282913): [<ffff80008b42e13c>] _raw_spin_lock_irqsave+0x2c/0x7c kernel/locking/spinlock.c:162
softirqs last enabled at (282904): [<ffff8000801f8e88>] softirq_handle_end kernel/softirq.c:400 [inline]
softirqs last enabled at (282904): [<ffff8000801f8e88>] handle_softirqs+0xa3c/0xbfc kernel/softirq.c:582
softirqs last disabled at (282909): [<ffff8000801fbdf8>] run_ksoftirqd+0x70/0x158 kernel/softirq.c:928
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&pch->downl);
<Interrupt>
lock(&pch->downl);
*** DEADLOCK ***
1 lock held by ksoftirqd/1/24:
#0: ffff80008f74dfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:325
stack backtrace:
CPU: 1 UID: 0 PID: 24 Comm: ksoftirqd/1 Not tainted 6.11.0-rc7-syzkaller-g5f5673607153 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:319
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:326
__dump_stack lib/dump_stack.c:93 [inline]
dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:119
dump_stack+0x1c/0x28 lib/dump_stack.c:128
print_usage_bug+0x698/0x9ac kernel/locking/lockdep.c:4000
mark_lock_irq+0x980/0xd2c
mark_lock+0x258/0x360 kernel/locking/lockdep.c:4677
__lock_acquire+0xf48/0x779c kernel/locking/lockdep.c:5096
lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5759
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x48/0x60 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
ppp_input+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304
ppp_async_process+0x98/0x150 drivers/net/ppp/ppp_async.c:495
tasklet_action_common+0x318/0x3f4 kernel/softirq.c:785
tasklet_action+0x68/0x8c kernel/softirq.c:811
handle_softirqs+0x2e4/0xbfc kernel/softirq.c:554
run_ksoftirqd+0x70/0x158 kernel/softirq.c:928
smpboot_thread_fn+0x4b0/0x90c kernel/smpboot.c:164
kthread+0x288/0x310 kernel/kthread.c:389
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
The Linux kernel CVE team has assigned CVE-2024-49946 to this issue.
Affected and fixed versions
===========================
Issue introduced in 5.11 with commit 4cf476ced45d and fixed in 5.15.168 with commit 176dd41e8c2b
Issue introduced in 5.11 with commit 4cf476ced45d and fixed in 6.1.113 with commit 635deca1800a
Issue introduced in 5.11 with commit 4cf476ced45d and fixed in 6.6.55 with commit f9620e2a665a
Issue introduced in 5.11 with commit 4cf476ced45d and fixed in 6.10.14 with commit efe9cc0f7c02
Issue introduced in 5.11 with commit 4cf476ced45d and fixed in 6.11.3 with commit c837f8583535
Issue introduced in 5.11 with commit 4cf476ced45d and fixed in 6.12-rc2 with commit aec7291003df
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-2024-49946
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:
drivers/net/ppp/ppp_generic.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/176dd41e8c2bd997ed3d66568a3362e69ecce99b
https://git.kernel.org/stable/c/635deca1800a68624f185dc1e04a8495b48cf185
https://git.kernel.org/stable/c/f9620e2a665aa642625bd2501282bbddff556bd7
https://git.kernel.org/stable/c/efe9cc0f7c0279216a5522271ec675b8288602e4
https://git.kernel.org/stable/c/c837f8583535f094a39386308c2ccfd92c8596cd
https://git.kernel.org/stable/c/aec7291003df78cb71fd461d7b672912bde55807
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