[syzbot] [fs?] [efi?] BUG: unable to handle kernel paging request in alloc_fs_context

[syzbot <syzbot+52cd651546d11d2af06b@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    c32f8dc5aaf9 Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1762d670580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ea4635ffd6ad5b4a
dashboard link: https://syzkaller.appspot.com/bug?extid=52cd651546d11d2af06b
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=165c0cd4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16f49cf4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b921498959d4/disk-c32f8dc5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/04e6ad946c4b/vmlinux-c32f8dc5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d4f0d8db50ee/Image-c32f8dc5.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+52cd651546d11d2af06b@syzkaller.appspotmail.com

efivarfs: resyncing variable state
Unable to handle kernel paging request at virtual address dfff800000000005
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
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, Xs = 0
[dfff800000000005] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 6487 Comm: syz-executor120 Not tainted 6.15.0-rc5-syzkaller-gc32f8dc5aaf9 #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : alloc_fs_context+0x1b4/0x76c fs/fs_context.c:294
lr : __lse_atomic64_add arch/arm64/include/asm/atomic_lse.h:134 [inline]
lr : arch_atomic64_add arch/arm64/include/asm/atomic.h:67 [inline]
lr : raw_atomic64_add include/linux/atomic/atomic-arch-fallback.h:2672 [inline]
lr : raw_atomic_long_add include/linux/atomic/atomic-long.h:121 [inline]
lr : atomic_long_add include/linux/atomic/atomic-instrumented.h:3261 [inline]
lr : get_cred_many include/linux/cred.h:203 [inline]
lr : get_cred include/linux/cred.h:218 [inline]
lr : alloc_fs_context+0x150/0x76c fs/fs_context.c:293
sp : ffff8000a31b7760
x29: ffff8000a31b7790 x28: dfff800000000000 x27: ffff0000c8ef88d8
x26: 0000000000000028 x25: ffff0000c7e6f4c8 x24: ffff80008fb953e0
x23: 0000000000000000 x22: ffff0000c7e6f498 x21: ffff0000c8ef8000
x20: 0000000000000000 x19: ffff0000c7e6f400 x18: 00000000ffffffff
x17: ffff800092f27000 x16: ffff80008adb31c0 x15: 0000000000000001
x14: 1fffe0001a05b0e0 x13: 0000000000000000 x12: 0000000000000000
x11: ffff60001a05b0e1 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : 0000000000000005 x7 : ffff80008022b2b8 x6 : ffff80008022b4b4
x5 : ffff0000dabc9c90 x4 : ffff8000a31b7520 x3 : ffff800080dfa950
x2 : 0000000000000001 x1 : 0000000000000008 x0 : 0000000000000001
Call trace:
 alloc_fs_context+0x1b4/0x76c fs/fs_context.c:294 (P)
 fs_context_for_mount+0x34/0x44 fs/fs_context.c:332
 vfs_kern_mount+0x38/0x178 fs/namespace.c:1313
 efivarfs_pm_notify+0x1c4/0x4b4 fs/efivarfs/super.c:529
 notifier_call_chain+0x1b8/0x4e4 kernel/notifier.c:85
 blocking_notifier_call_chain+0x70/0xa0 kernel/notifier.c:380
 pm_notifier_call_chain+0x2c/0x3c kernel/power/main.c:109
 snapshot_release+0x104/0x1c4 kernel/power/user.c:125
 __fput+0x340/0x75c fs/file_table.c:465
 ____fput+0x20/0x58 fs/file_table.c:493
 task_work_run+0x1dc/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x4e8/0x1998 kernel/exit.c:953
 do_group_exit+0x194/0x22c kernel/exit.c:1102
 __do_sys_exit_group kernel/exit.c:1113 [inline]
 __se_sys_exit_group kernel/exit.c:1111 [inline]
 pid_child_should_wake+0x0/0x1dc kernel/exit.c:1111
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767
 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
Code: 97f8a879 f9400368 9100a11a d343ff48 (387c6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	97f8a879 	bl	0xffffffffffe2a1e4
   4:	f9400368 	ldr	x8, [x27]
   8:	9100a11a 	add	x26, x8, #0x28
   c:	d343ff48 	lsr	x8, x26, #3
* 10:	387c6908 	ldrb	w8, [x8, x28] <-- trapping instruction


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup