BUG: unable to handle kernel NULL pointer dereference in io_uring_cancel_task_requests

[Hao Sun]

Hi

When using Healer(https://github.com/SunHao-0/healer/tree/dev) to fuzz
the Linux kernel, I found a null-ptr-deref bug in
io_uring_cancel_task_requests under fault injection condition, but I'm
not sure about this.
Sorry, I do not have a reproducing program for this bug.
I hope that the stack trace information in the crash log can help you
locate the problem.

Here is the details:
commit:   3b9cdafb5358eb9f3790de2f728f765fef100731
version:   linux 5.11
git tree:    upstream
Full log can be found in the attachment.

Fault injection log:
FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 0
CPU: 1 PID: 9161 Comm: executor Not tainted 5.11.0+ #5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x137/0x194 lib/dump_stack.c:120
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail+0x23e/0x250 lib/fault-inject.c:146
 should_fail_usercopy+0x16/0x20 lib/fault-inject-usercopy.c:37
 _copy_from_user+0x1c/0xd0 lib/usercopy.c:14
 copy_from_user include/linux/uaccess.h:192 [inline]
 set_user_sigmask+0x4b/0x110 kernel/signal.c:3015
 io_cqring_wait+0x2e3/0x8b0 fs/io_uring.c:7250
 __do_sys_io_uring_enter fs/io_uring.c:9480 [inline]
 __se_sys_io_uring_enter+0x8fc/0xb70 fs/io_uring.c:9397
 __x64_sys_io_uring_enter+0x74/0x80 fs/io_uring.c:9397
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x46a379
Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f046fa19c58 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: ffffffffffffffda RBX: 000000000078c080 RCX: 000000000046a379
RDX: 00000000000066ab RSI: 0000000000000001 RDI: 0000000000000003
RBP: 00007f046fa19c90 R08: 0000000020000040 R09: 0000000000000008
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 000000000078c080 R15: 00007fff769deef0

Crash log:
BUG: kernel NULL pointer dereference, address: 0000000000000040
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 49954067 P4D 49954067 PUD 45f92067 PMD 0
Oops: 0000 [#1] PREEMPT SMP
CPU: 1 PID: 9161 Comm: executor Not tainted 5.11.0+ #5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:io_uring_cancel_task_requests+0x3f/0x990 fs/io_uring.c:9045
Code: 48 8b 04 25 28 00 00 00 48 89 44 24 68 e8 89 e6 c5 ff 65 4c 8b
34 25 00 6d 01 00 49 8d 7c 24 40 48 89 7c 24 30 e8 81 97 d6 ff <41> 8b
5c 24 40 89 de 83 e6 02 31 ff e8 70 ea c5 ff 83 e3 02 48 89
RSP: 0018:ffffc90002a97b48 EFLAGS: 00010246
RAX: ffff88804b8e0d38 RBX: ffff88804b8ad700 RCX: 0000000000000764
RDX: 0000000000000040 RSI: ffff8880409d5140 RDI: 0000000000000040
RBP: ffff8880409d5140 R08: 0000000000000000 R09: 0000000000000043
R10: 0001ffffffffffff R11: ffff88804b8e0280 R12: 0000000000000000
R13: ffff8880409d5140 R14: ffff88804b8e0280 R15: ffff8880481c1800
FS:  00007f046fa1a700(0000) GS:ffff88807ec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000040 CR3: 00000000479a5000 CR4: 0000000000750ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 __io_uring_files_cancel+0x9b/0x200 fs/io_uring.c:9140
 io_uring_files_cancel include/linux/io_uring.h:65 [inline]
 do_exit+0x1a8/0x16d0 kernel/exit.c:780
 do_group_exit+0xc5/0x180 kernel/exit.c:922
 get_signal+0xd90/0x1470 kernel/signal.c:2773
 arch_do_signal_or_restart+0x2a/0x260 arch/x86/kernel/signal.c:811
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x109/0x1a0 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x46a379
Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f046fa19cd8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000078c080 RCX: 000000000046a379
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000078c088
RBP: 000000000078c088 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078c08c
R13: 0000000000000000 R14: 000000000078c080 R15: 00007fff769deef0
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
CR2: 0000000000000040
---[ end trace 613db1a25ecf6443 ]---
RIP: 0010:io_uring_cancel_task_requests+0x3f/0x990 fs/io_uring.c:9045
Code: 48 8b 04 25 28 00 00 00 48 89 44 24 68 e8 89 e6 c5 ff 65 4c 8b
34 25 00 6d 01 00 49 8d 7c 24 40 48 89 7c 24 30 e8 81 97 d6 ff <41> 8b
5c 24 40 89 de 83 e6 02 31 ff e8 70 ea c5 ff 83 e3 02 48 89
RSP: 0018:ffffc90002a97b48 EFLAGS: 00010246
RAX: ffff88804b8e0d38 RBX: ffff88804b8ad700 RCX: 0000000000000764
RDX: 0000000000000040 RSI: ffff8880409d5140 RDI: 0000000000000040
RBP: ffff8880409d5140 R08: 0000000000000000 R09: 0000000000000043
R10: 0001ffffffffffff R11: ffff88804b8e0280 R12: 0000000000000000
R13: ffff8880409d5140 R14: ffff88804b8e0280 R15: ffff8880481c1800
FS:  00007f046fa1a700(0000) GS:ffff88807ec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000040 CR3: 00000000479a5000 CR4: 0000000000750ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554

Attachment: log
Description: Binary data