general protection fault in fsinfo_generic_mount_all

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4993e4fe Add linux-next specific files for 20200814
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1458b25e900000
kernel config: https://syzkaller.appspot.com/x/.config?x=2055bd0d83d5ee16
dashboard link: https://syzkaller.appspot.com/bug?extid=4d81cafddaa5f9dd1827
compiler: gcc (GCC) 10.1.0-syz 20200507
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4d81ca...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
CPU: 1 PID: 32746 Comm: syz-executor.3 Not tainted 5.8.0-next-20200814-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:fsinfo_generic_mount_all+0x29c/0x510 fs/namespace.c:4524
Code: ab ff 48 c7 c7 c0 38 d4 89 e8 50 26 2d 06 48 8d 43 28 48 89 c2 48 89 85 48 ff ff ff 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 40 02 00 00 48 8b 43 28 48 39 85 48 ff ff ff 48
RSP: 0018:ffffc900095e7c08 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff87f667da
RDX: 0000000000000005 RSI: 0000000000000008 RDI: ffffffff89d438c8
RBP: ffffc900095e7cd8 R08: 0000000000000001 R09: ffffffff89d438cf
R10: fffffbfff13a8719 R11: 0000000000000000 R12: ffffc900095e7c48
R13: ffffc900095e7e40 R14: 0000000000000001 R15: 0000000000000001
FS: 00007f3d26fd8700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31122000 CR3: 000000008e39f000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
fsinfo_get_this_attribute fs/fsinfo.c:346 [inline]
fsinfo_get_attribute+0x814/0x9c0 fs/fsinfo.c:425
fsinfo_call fs/fsinfo.c:445 [inline]
fsinfo_call+0xf3/0x1d0 fs/fsinfo.c:436
vfs_fsinfo fs/fsinfo.c:519 [inline]
vfs_fsinfo+0x204/0x3d0 fs/fsinfo.c:493
vfs_fsinfo_path fs/fsinfo.c:570 [inline]
__do_sys_fsinfo+0x64e/0x990 fs/fsinfo.c:708
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45d239
Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f3d26fd7c78 EFLAGS: 00000246 ORIG_RAX: 00000000000001b9
RAX: ffffffffffffffda RBX: 0000000000003b80 RCX: 000000000045d239
RDX: 0000000020000440 RSI: 0000000020000000 RDI: 0000000000000005
RBP: 000000000118cf98 R08: 0000000020000480 R09: 0000000000000048
R10: 0000000000000020 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffe57ad993f R14: 00007f3d26fd89c0 R15: 000000000118cf4c
Modules linked in:
---[ end trace 49364ce07c7bfd6c ]---
RIP: 0010:fsinfo_generic_mount_all+0x29c/0x510 fs/namespace.c:4524
Code: ab ff 48 c7 c7 c0 38 d4 89 e8 50 26 2d 06 48 8d 43 28 48 89 c2 48 89 85 48 ff ff ff 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 40 02 00 00 48 8b 43 28 48 39 85 48 ff ff ff 48
RSP: 0018:ffffc900095e7c08 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff87f667da
RDX: 0000000000000005 RSI: 0000000000000008 RDI: ffffffff89d438c8
RBP: ffffc900095e7cd8 R08: 0000000000000001 R09: ffffffff89d438cf
R10: fffffbfff13a8719 R11: 0000000000000000 R12: ffffc900095e7c48
R13: ffffc900095e7e40 R14: 0000000000000001 R15: 0000000000000001
FS: 00007f3d26fd8700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001590004 CR3: 000000008e39f000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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[Dmitry Vyukov]

Rumors say fsinfo was removed from linux-next:

#syz invalid

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