6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kuniyuki Iwashima kuniyu@amazon.com
[ Upstream commit 94b0818fa63555a65f6ba107080659ea6bcca63e ]
syzbot reported a warning in bcm_release(). [0]
The blamed change fixed another warning that is triggered when connect() is issued again for a socket whose connect()ed device has been unregistered.
However, if the socket is just close()d without the 2nd connect(), the remaining bo->bcm_proc_read triggers unnecessary remove_proc_entry() in bcm_release().
Let's clear bo->bcm_proc_read after remove_proc_entry() in bcm_notify().
[0] name '4986' WARNING: CPU: 0 PID: 5234 at fs/proc/generic.c:711 remove_proc_entry+0x2e7/0x5d0 fs/proc/generic.c:711 Modules linked in: CPU: 0 UID: 0 PID: 5234 Comm: syz-executor606 Not tainted 6.11.0-rc5-syzkaller-00178-g5517ae241919 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 RIP: 0010:remove_proc_entry+0x2e7/0x5d0 fs/proc/generic.c:711 Code: ff eb 05 e8 cb 1e 5e ff 48 8b 5c 24 10 48 c7 c7 e0 f7 aa 8e e8 2a 38 8e 09 90 48 c7 c7 60 3a 1b 8c 48 89 de e8 da 42 20 ff 90 <0f> 0b 90 90 48 8b 44 24 18 48 c7 44 24 40 0e 36 e0 45 49 c7 04 07 RSP: 0018:ffffc9000345fa20 EFLAGS: 00010246 RAX: 2a2d0aee2eb64600 RBX: ffff888032f1f548 RCX: ffff888029431e00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc9000345fb08 R08: ffffffff8155b2f2 R09: 1ffff1101710519a R10: dffffc0000000000 R11: ffffed101710519b R12: ffff888011d38640 R13: 0000000000000004 R14: 0000000000000000 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880b8800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fcfb52722f0 CR3: 000000000e734000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> bcm_release+0x250/0x880 net/can/bcm.c:1578 __sock_release net/socket.c:659 [inline] sock_close+0xbc/0x240 net/socket.c:1421 __fput+0x24a/0x8a0 fs/file_table.c:422 task_work_run+0x24f/0x310 kernel/task_work.c:228 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0xa2f/0x27f0 kernel/exit.c:882 do_group_exit+0x207/0x2c0 kernel/exit.c:1031 __do_sys_exit_group kernel/exit.c:1042 [inline] __se_sys_exit_group kernel/exit.c:1040 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1040 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232 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: 0033:0x7fcfb51ee969 Code: Unable to access opcode bytes at 0x7fcfb51ee93f. RSP: 002b:00007ffce0109ca8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fcfb51ee969 RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000001 RBP: 00007fcfb526f3b0 R08: ffffffffffffffb8 R09: 0000555500000000 R10: 0000555500000000 R11: 0000000000000246 R12: 00007fcfb526f3b0 R13: 0000000000000000 R14: 00007fcfb5271ee0 R15: 00007fcfb51bf160 </TASK>
Fixes: 76fe372ccb81 ("can: bcm: Remove proc entry when dev is unregistered.") Reported-by: syzbot+0532ac7a06fb1a03187e@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=0532ac7a06fb1a03187e Tested-by: syzbot+0532ac7a06fb1a03187e@syzkaller.appspotmail.com Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.com Reviewed-by: Vincent Mailhol mailhol.vincent@wanadoo.fr Link: https://patch.msgid.link/20240905012237.79683-1-kuniyu@amazon.com Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de Signed-off-by: Sasha Levin sashal@kernel.org --- net/can/bcm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/can/bcm.c b/net/can/bcm.c index 00208ee13e578..a1f5db0fd5d4f 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -1429,8 +1429,10 @@ static void bcm_notify(struct bcm_sock *bo, unsigned long msg, /* remove device reference, if this is our bound device */ if (bo->bound && bo->ifindex == dev->ifindex) { #if IS_ENABLED(CONFIG_PROC_FS) - if (sock_net(sk)->can.bcmproc_dir && bo->bcm_proc_read) + if (sock_net(sk)->can.bcmproc_dir && bo->bcm_proc_read) { remove_proc_entry(bo->procname, sock_net(sk)->can.bcmproc_dir); + bo->bcm_proc_read = NULL; + } #endif bo->bound = 0; bo->ifindex = 0;