general protection fault in do_syscall_64

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: b98aebd2 Linux 4.14.150
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=159cc1d0e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=c52c93b368dac5a7
dashboard link: https://syzkaller.appspot.com/bug?extid=cb20358b22a4975c34a1
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+cb2035...@syzkaller.appspotmail.com

kasan: GPF could be caused by NULL-ptr deref or user memory access
kmalloc include/linux/slab.h:493 [inline]
simple_xattr_alloc+0x31/0xa0 fs/xattr.c:822
simple_xattr_set+0x3f/0x590 fs/xattr.c:881
kernfs_xattr_set+0x8a/0xb0 fs/kernfs/inode.c:336
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
__vfs_setxattr+0xd8/0x130 fs/xattr.c:150
CPU: 1 PID: 17221 Comm: syz-executor.5 Not tainted 4.14.150 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
__vfs_setxattr_noperm+0x102/0x3c0 fs/xattr.c:181
task: ffff888099ac61c0 task.stack: ffff888064fc0000
vfs_setxattr+0xc5/0xf0 fs/xattr.c:224
RIP: 0010:__list_del_entry_valid+0x85/0xf5 lib/list_debug.c:51
setxattr+0x1de/0x350 fs/xattr.c:453
RSP: 0018:ffff888064fc7b30 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 00000000fffffff4 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88808ee90120
RBP: ffff888064fc7b48 R08: dffffc0000000000 R09: ffffffff88c9f878
R10: ffff888064fc7b48 R11: ffff888099ac61c0 R12: 0000000000000000
R13: 0000000000000000 R14: ffff88808ee90118 R15: ffff88808ee90120
FS: 00007f7361855700(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000
path_setxattr+0x11f/0x140 fs/xattr.c:472
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000dbe470 CR3: 000000006ae14000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
SYSC_lsetxattr fs/xattr.c:494 [inline]
SyS_lsetxattr+0x38/0x50 fs/xattr.c:490
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
__list_del_entry include/linux/list.h:117 [inline]
list_del include/linux/list.h:125 [inline]
kernfs_kill_sb+0x62/0x1e0 fs/kernfs/mount.c:365
entry_SYSCALL_64_after_hwframe+0x42/0xb7
sysfs_kill_sb+0x23/0x40 fs/sysfs/mount.c:53
RIP: 0033:0x459f49
deactivate_locked_super+0x74/0xe0 fs/super.c:319
RSP: 002b:00007fec9efa5c78 EFLAGS: 00000246
sget_userns+0x9d9/0xc30 fs/super.c:537
ORIG_RAX: 00000000000000bd
RAX: ffffffffffffffda RBX: 00007fec9efa5c90 RCX: 0000000000459f49
RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000020000040
kernfs_mount_ns+0xe9/0x790 fs/kernfs/mount.c:324
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
sysfs_mount+0xaa/0x170 fs/sysfs/mount.c:39
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fec9efa66d4
R13: 00000000004cf6c0 R14: 00000000004dbb00 R15: 0000000000000003
mount_fs+0x97/0x2a1 fs/super.c:1237
vfs_kern_mount.part.0+0x5e/0x3d0 fs/namespace.c:1046
vfs_kern_mount fs/namespace.c:1036 [inline]
do_new_mount fs/namespace.c:2549 [inline]
do_mount+0x417/0x27d0 fs/namespace.c:2879
SYSC_mount fs/namespace.c:3095 [inline]
SyS_mount+0xab/0x120 fs/namespace.c:3072
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459f49
RSP: 002b:00007f7361854c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f7361854c90 RCX: 0000000000459f49
RDX: 0000000020000500 RSI: 0000000020000480 RDI: 0000000000000000
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f73618556d4
R13: 00000000004c69b2 R14: 00000000004dbe18 R15: 0000000000000004
Code: c5 0f 84 e1 00 00 00 48 b8 00 02 00 00 00 00 ad de 49 39 c4 0f 84 e2
00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00
75 53 49 8b 14 24 4c 39 f2 0f 85 99 00 00 00 49 8d
RIP: __list_del_entry_valid+0x85/0xf5 lib/list_debug.c:51 RSP:
ffff888064fc7b30
---[ end trace ef54147555785999 ]---


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.