On 09/01/2021 16:27, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:36bbbd0e Merge branch 'rcu/urgent' of git://git.kernel.org..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=149afeeb50
> kernel config: https://syzkaller.appspot.com/x/.config?x=8aa30b9da402d224
> dashboard link: https://syzkaller.appspot.com/bug?extid=99ed55100402022a6276
> compiler: gcc (GCC) 10.1.0-syz 20200507
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10496f70d0
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10cedf70d0
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+99ed55100402022a6...@syzkaller.appspotmail.com
> Fixes: 4d004099a668 ("lockdep: Fix lockdep recursion")
Looks like the fixed ERR_PTR vs NULL issue.
#syz test: git://git.kernel.dk/linux-block
d9d05217cb6990b9a56e13b56e7a1b71e2551f6c
>
> RBP: 0005 R08: 0001 R09: 00401140
> R10: R11: 0246 R12: 00402860
> R13: 004028f0 R14: R15:
> BUG: unable to handle page fault for address: fffc
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x) - not-present page
> PGD b08f067 P4D b08f067 PUD b091067 PMD 0
> Oops: [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 8500 Comm: syz-executor191 Not tainted 5.11.0-rc2-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> RIP: 0010:percpu_ref_exit+0x2f/0x140 lib/percpu-refcount.c:130
> Code: 54 55 53 48 89 fb e8 f0 fc b6 fd 48 8d 6b 08 48 b8 00 00 00 00 00 fc ff
> df 48 89 ea 48 c1 ea 03 80 3c 02 00 0f 85 d5 00 00 00 <4c> 8b 73 08 48 89 df
> e8 c5 fe ff ff 4d 85 f6 0f 84 b3 00 00 00 e8
> RSP: 0018:c9000126fcc8 EFLAGS: 00010246
> RAX: dc00 RBX: fff4 RCX:
> RDX: 1fff RSI: 83bb78b0 RDI: fff4
> RBP: fffc R08: 0001 R09: 8ebda867
> R10: fbfff1d7b50c R11: R12:
> R13: 88801adee000 R14: 0002 R15: fff4
> FS: 0179f940() GS:8880b9e0() knlGS:
> CS: 0010 DS: ES: CR0: 80050033
> CR2: fffc CR3: 2027 CR4: 001506f0
> DR0: DR1: DR2:
> DR3: DR6: fffe0ff0 DR7: 0400
> Call Trace:
> destroy_fixed_file_ref_node fs/io_uring.c:7703 [inline]
> io_sqe_files_unregister+0x30b/0x770 fs/io_uring.c:7293
> __io_uring_register fs/io_uring.c:9916 [inline]
> __do_sys_io_uring_register+0x1185/0x4080 fs/io_uring.c:1
> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x444df9
> Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 db d5 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:7ffeb192ade8 EFLAGS: 0246 ORIG_RAX: 01ab
> RAX: ffda RBX: 7ffeb192ae90 RCX: 00444df9
> RDX: RSI: 0003 RDI: 0004
> RBP: 0005 R08: 0001 R09: 00401140
> R10: R11: 0246 R12: 00402860
> R13: 004028f0 R14: R15:
> Modules linked in:
> CR2: fffc
> ---[ end trace ed34d5d65a155c02 ]---
> RIP: 0010:percpu_ref_exit+0x2f/0x140 lib/percpu-refcount.c:130
> Code: 54 55 53 48 89 fb e8 f0 fc b6 fd 48 8d 6b 08 48 b8 00 00 00 00 00 fc ff
> df 48 89 ea 48 c1 ea 03 80 3c 02 00 0f 85 d5 00 00 00 <4c> 8b 73 08 48 89 df
> e8 c5 fe ff ff 4d 85 f6 0f 84 b3 00 00 00 e8
> RSP: 0018:c9000126fcc8 EFLAGS: 00010246
> RAX: dc00 RBX: fff4 RCX:
> RDX: 1fff RSI: 83bb78b0 RDI: fff4
> RBP: fffc R08: 0001 R09: 8ebda867
> R10: fbfff1d7b50c R11: R12:
> R13: 88801adee000 R14: 0002 R15: fff4
> FS: 0179f940() GS:8880b9e0() knlGS:
> CS: 0010 DS: ES: CR0: 80050033
> CR2: fffc CR3: 2027 CR4: 001506f0
> DR0: DR1: DR2:
> DR3: DR6: fffe0ff0 DR7: 0400
>
>
> ---
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