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Date: Mon, 24 Jul 2023 14:49:28 +0200
From: Oliver Hartkopp <socketcan@...tkopp.net>
To: Eric Dumazet <edumazet@...gle.com>, "David S . Miller"
<davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, linux-can@...r.kernel.org,
eric.dumazet@...il.com, syzbot <syzkaller@...glegroups.com>,
Ziyang Xuan <william.xuanziyang@...wei.com>, stable@...r.kernel.org,
Marc Kleine-Budde <mkl@...gutronix.de>
Subject: Re: [PATCH net] can: raw: fix lockdep issue in raw_release()
Hello Eric, Jakub,
the patch that needs to be fixed here is currently already on its way
into the stable trees:
> Fixes: ee8b94c8510c ("can: raw: fix receiver memory leak")
Should this patch go through the linux-can tree or would somebody like
to apply it directly to the net tree?
Many thanks,
Oliver
On 20.07.23 13:44, Eric Dumazet wrote:
> syzbot complained about a lockdep issue [1]
>
> Since raw_bind() and raw_setsockopt() first get RTNL
> before locking the socket, we must adopt the same order in raw_release()
>
> [1]
> WARNING: possible circular locking dependency detected
> 6.5.0-rc1-syzkaller-00192-g78adb4bcf99e #0 Not tainted
> ------------------------------------------------------
> syz-executor.0/14110 is trying to acquire lock:
> ffff88804e4b6130 (sk_lock-AF_CAN){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1708 [inline]
> ffff88804e4b6130 (sk_lock-AF_CAN){+.+.}-{0:0}, at: raw_bind+0xb1/0xab0 net/can/raw.c:435
>
> but task is already holding lock:
> ffffffff8e3df368 (rtnl_mutex){+.+.}-{3:3}, at: raw_bind+0xa7/0xab0 net/can/raw.c:434
>
> which lock already depends on the new lock.
>
> the existing dependency chain (in reverse order) is:
>
> -> #1 (rtnl_mutex){+.+.}-{3:3}:
> __mutex_lock_common kernel/locking/mutex.c:603 [inline]
> __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
> raw_release+0x1c6/0x9b0 net/can/raw.c:391
> __sock_release+0xcd/0x290 net/socket.c:654
> sock_close+0x1c/0x20 net/socket.c:1386
> __fput+0x3fd/0xac0 fs/file_table.c:384
> task_work_run+0x14d/0x240 kernel/task_work.c:179
> resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
> exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
> exit_to_user_mode_prepare+0x210/0x240 kernel/entry/common.c:204
> __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
> syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297
> do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> -> #0 (sk_lock-AF_CAN){+.+.}-{0:0}:
> check_prev_add kernel/locking/lockdep.c:3142 [inline]
> check_prevs_add kernel/locking/lockdep.c:3261 [inline]
> validate_chain kernel/locking/lockdep.c:3876 [inline]
> __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5144
> lock_acquire kernel/locking/lockdep.c:5761 [inline]
> lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5726
> lock_sock_nested+0x3a/0xf0 net/core/sock.c:3492
> lock_sock include/net/sock.h:1708 [inline]
> raw_bind+0xb1/0xab0 net/can/raw.c:435
> __sys_bind+0x1ec/0x220 net/socket.c:1792
> __do_sys_bind net/socket.c:1803 [inline]
> __se_sys_bind net/socket.c:1801 [inline]
> __x64_sys_bind+0x72/0xb0 net/socket.c:1801
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> other info that might help us debug this:
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(rtnl_mutex);
> lock(sk_lock-AF_CAN);
> lock(rtnl_mutex);
> lock(sk_lock-AF_CAN);
>
> *** DEADLOCK ***
>
> 1 lock held by syz-executor.0/14110:
>
> stack backtrace:
> CPU: 0 PID: 14110 Comm: syz-executor.0 Not tainted 6.5.0-rc1-syzkaller-00192-g78adb4bcf99e #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:88 [inline]
> dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
> check_noncircular+0x311/0x3f0 kernel/locking/lockdep.c:2195
> check_prev_add kernel/locking/lockdep.c:3142 [inline]
> check_prevs_add kernel/locking/lockdep.c:3261 [inline]
> validate_chain kernel/locking/lockdep.c:3876 [inline]
> __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5144
> lock_acquire kernel/locking/lockdep.c:5761 [inline]
> lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5726
> lock_sock_nested+0x3a/0xf0 net/core/sock.c:3492
> lock_sock include/net/sock.h:1708 [inline]
> raw_bind+0xb1/0xab0 net/can/raw.c:435
> __sys_bind+0x1ec/0x220 net/socket.c:1792
> __do_sys_bind net/socket.c:1803 [inline]
> __se_sys_bind net/socket.c:1801 [inline]
> __x64_sys_bind+0x72/0xb0 net/socket.c:1801
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7fd89007cb29
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fd890d2a0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
> RAX: ffffffffffffffda RBX: 00007fd89019bf80 RCX: 00007fd89007cb29
> RDX: 0000000000000010 RSI: 0000000020000040 RDI: 0000000000000003
> RBP: 00007fd8900c847a R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 000000000000000b R14: 00007fd89019bf80 R15: 00007ffebf8124f8
> </TASK>
>
> Fixes: ee8b94c8510c ("can: raw: fix receiver memory leak")
> Reported-by: syzbot <syzkaller@...glegroups.com>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Ziyang Xuan <william.xuanziyang@...wei.com>
> Cc: Oliver Hartkopp <socketcan@...tkopp.net>
> Cc: stable@...r.kernel.org
> Cc: Marc Kleine-Budde <mkl@...gutronix.de>
> ---
> net/can/raw.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/net/can/raw.c b/net/can/raw.c
> index 2302e48829677334f8b2d74a479e5a9cbb5ce03c..ba6b52b1d7767fdd7b57d1b8e5519495340c572c 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -386,9 +386,9 @@ static int raw_release(struct socket *sock)
> list_del(&ro->notifier);
> spin_unlock(&raw_notifier_lock);
>
> + rtnl_lock();
> lock_sock(sk);
>
> - rtnl_lock();
> /* remove current filters & unregister */
> if (ro->bound) {
> if (ro->dev)
> @@ -405,12 +405,13 @@ static int raw_release(struct socket *sock)
> ro->dev = NULL;
> ro->count = 0;
> free_percpu(ro->uniq);
> - rtnl_unlock();
>
> sock_orphan(sk);
> sock->sk = NULL;
>
> release_sock(sk);
> + rtnl_unlock();
> +
> sock_put(sk);
>
> return 0;
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