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BUG: unable to handle kernel NULL pointer dereference in io_do_iopoll

Status: fixed on 2023/02/24 13:50
Subsystems: fs io-uring
[Documentation on labels]
Reported-by: syzbot+1a0a53300ce782f8b3ad@syzkaller.appspotmail.com
Fix commit: aa184e8671f0 io_uring: don't attempt to IOPOLL for MSG_RING requests
First crash: 936d, last: 936d
Cause bisection: introduced by (bisect log) :
commit 3f1d52abf098c85b177b8c6f5b310e8347d1bc42
Author: Jens Axboe <axboe@kernel.dk>
Date: Tue Mar 29 16:43:56 2022 +0000

  io_uring: defer msg-ring file validity check until command issue

Crash: BUG: unable to handle kernel NULL pointer dereference in io_do_iopoll (log)
Repro: C syz .config
  
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[syzbot] BUG: unable to handle kernel NULL pointer dereference in io_do_iopoll 2 (5) 2022/05/17 19:02
[PATCH] io_uring: don't attempt to IOPOLL for MSG_RING requests 2 (2) 2022/05/17 18:48
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2022/05/17 18:46 15m axboe@kernel.dk git://git.kernel.dk/linux-block io_uring-5.18 OK
2022/05/17 18:34 9m axboe@kernel.dk git://git.kernel.dk/linux-block io_uring-5.18 report log

Sample crash report:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 0 P4D 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3597 Comm: syz-executor652 Not tainted 5.18.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90002f4fb68 EFLAGS: 00010246
RAX: ffffffff89dad220 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000003 RSI: ffffc90002f4fbe0 RDI: ffff888019b838c0
RBP: ffff888019b83901 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff81ec11a0 R11: 0000000000000000 R12: 0000000000000003
R13: ffffc90002f4fbe0 R14: ffff888019b838c0 R15: ffff888019b83938
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000000ba8e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 io_do_iopoll+0x262/0x1080 fs/io_uring.c:2776
 io_iopoll_try_reap_events+0xba/0x158 fs/io_uring.c:2829
 io_ring_ctx_wait_and_kill+0x1d9/0x327 fs/io_uring.c:10167
 io_uring_release+0x42/0x46 fs/io_uring.c:10184
 __fput+0x277/0x9d0 fs/file_table.c:317
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:37 [inline]
 do_exit+0xaff/0x2a00 kernel/exit.c:795
 do_group_exit+0xd2/0x2f0 kernel/exit.c:925
 __do_sys_exit_group kernel/exit.c:936 [inline]
 __se_sys_exit_group kernel/exit.c:934 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:934
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f6ba5d6ff19
Code: Unable to access opcode bytes at RIP 0x7f6ba5d6feef.
RSP: 002b:00007ffee0f8cb58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f6ba5de4290 RCX: 00007f6ba5d6ff19
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6ba5de4290
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90002f4fb68 EFLAGS: 00010246
RAX: ffffffff89dad220 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000003 RSI: ffffc90002f4fbe0 RDI: ffff888019b838c0
RBP: ffff888019b83901 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff81ec11a0 R11: 0000000000000000 R12: 0000000000000003
R13: ffffc90002f4fbe0 R14: ffff888019b838c0 R15: ffff888019b83938
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000000ba8e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/05/16 16:34 upstream 42226c989789 744a39e2 .config strace log report syz C ci-upstream-kasan-gce BUG: unable to handle kernel NULL pointer dereference in io_do_iopoll
2022/05/16 15:06 upstream 42226c989789 744a39e2 .config strace log report syz C ci-upstream-kasan-gce-root BUG: unable to handle kernel NULL pointer dereference in io_do_iopoll
2022/05/16 14:43 upstream 42226c989789 744a39e2 .config console log report info ci-upstream-kasan-gce-root BUG: unable to handle kernel NULL pointer dereference in io_do_iopoll
* Struck through repros no longer work on HEAD.