Patch "can: raw: fix lockdep issue in raw_release()" has been added to the 5.15-stable tree

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This is a note to let you know that I've just added the patch titled

    can: raw: fix lockdep issue in raw_release()

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     can-raw-fix-lockdep-issue-in-raw_release.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit eb8eae370d5b4a930dba57949411b2244340a45f
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date:   Thu Jul 20 11:44:38 2023 +0000

    can: raw: fix lockdep issue in raw_release()
    
    [ Upstream commit 11c9027c983e9e4b408ee5613b6504d24ebd85be ]
    
    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@xxxxxxxxxxxxxxxx>
    Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
    Cc: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx>
    Cc: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
    Cc: stable@xxxxxxxxxxxxxxx
    Cc: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/all/20230720114438.172434-1-edumazet@xxxxxxxxxx
    Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/can/raw.c b/net/can/raw.c
index afa76ce0bf608..c02df37894ff9 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -383,9 +383,9 @@ 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)
@@ -402,12 +402,13 @@ 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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