Re: [syzbot] [block?] BUG: unable to handle kernel paging request in blk_mq_complete_request_remote

[syzbot <syzbot+2e3bf0bd49acd9b21d4b@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: unable to handle kernel paging request in tomoyo_realpath_from_path

Unable to handle kernel paging request at virtual address dfff80000000000c
KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
Mem abort info:
  ESR = 0x0000000096000005
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x05: level 1 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0
[dfff80000000000c] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 5306 Comm: syz-executor Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : tomoyo_realpath_from_path+0x1a0/0x4dc security/tomoyo/realpath.c:265
lr : tomoyo_realpath_from_path+0x140/0x4dc security/tomoyo/realpath.c:257
sp : ffff800093a67510
x29: ffff800093a67540 x28: ffff0000c39b8fff x27: dfff800000000000
x26: 0000000000000fff x25: 0000000000000060 x24: 0000000000001000
x23: 1fffe0001e436caf x22: ffff0000d3d16090 x21: ffff0000c39b8000
x20: ffff0000f21b64e0 x19: ffff0000d3d16050 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000001
x14: 00000000ffff8000 x13: 00000000ac727a19 x12: ffff800080021608
x11: ffff800080021608 x10: 0000000000000003 x9 : 0000000000000000
x8 : 000000000000000c x7 : 0000000000000000 x6 : 000000000000003f
x5 : 00000000ffffffff x4 : 0000000000000c40 x3 : 0000000000002000
x2 : 0000000000001000 x1 : ffff0000c8e2bb00 x0 : 0000000000000000
Call trace:
 tomoyo_realpath_from_path+0x1a0/0x4dc security/tomoyo/realpath.c:265 (P)
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_check_open_permission+0x1c4/0x394 security/tomoyo/file.c:776
 tomoyo_file_open+0x78/0xcc security/tomoyo/tomoyo.c:334
 security_file_open+0xbc/0x258 security/security.c:2760
 do_dentry_open+0x2a0/0xfb4 fs/open.c:977
 vfs_open_consume+0x54/0x2ec fs/open.c:1131
 do_open fs/namei.c:4851 [inline]
 path_openat+0x1098/0x1910 fs/namei.c:5016
 do_file_open+0x1c8/0x2e8 fs/namei.c:5045
 do_sys_openat2+0x114/0x1ec fs/open.c:1442
 do_sys_open+0xb0/0xe0 fs/open.c:1448
 __do_sys_openat fs/open.c:1464 [inline]
 __se_sys_openat fs/open.c:1459 [inline]
 __arm64_sys_openat+0xa8/0xc4 fs/open.c:1459
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:797
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:816
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606
Code: 97d64865 f9400328 91018119 d343ff28 (387b6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	97d64865 	bl	0xffffffffff592194
   4:	f9400328 	ldr	x8, [x25]
   8:	91018119 	add	x25, x8, #0x60
   c:	d343ff28 	lsr	x8, x25, #3
* 10:	387b6908 	ldrb	w8, [x8, x27] <-- trapping instruction


Tested on:

commit:         58c1eb84 arm64: sdei: Preserve the interrupted context..
git tree:       https://github.com/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=141d05a1580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a58b6b4d667e7a61
dashboard link: https://syzkaller.appspot.com/bug?extid=2e3bf0bd49acd9b21d4b
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1141b4c3580000