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

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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    a1c24ab82279 Merge branch 'for-next/el2-enable-feat-pmuv3p..
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=127d53b8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f6b108de97771157
dashboard link: https://syzkaller.appspot.com/bug?extid=00d13e505ef530a45100
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17e7a7a4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17457498580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9581dbc26f55/disk-a1c24ab8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/50aec9ab8b8b/vmlinux-a1c24ab8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3a018984f8f5/Image-a1c24ab8.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+00d13e505ef530a45100@syzkaller.appspotmail.com

random: crng reseeded on system resumption
Unable to handle kernel paging request at virtual address dfff80000000000d
KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
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
[dfff80000000000d] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 UID: 0 PID: 6436 Comm: syz-executor261 Not tainted 6.14.0-rc3-syzkaller-ga1c24ab82279 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : efivarfs_pm_notify+0xcc/0x350 fs/efivarfs/super.c:480
lr : efivarfs_pm_notify+0x8c/0x350 fs/efivarfs/super.c:477
sp : ffff80009cba7260
x29: ffff80009cba7300 x28: 0000000000000000 x27: 1fffe00019fdce21
x26: dfff800000000000 x25: ffff700013974e4c x24: 0000000000000068
x23: ffff80009cba7288 x22: 0000000000000005 x21: ffff80009cba7280
x20: ffff80009cba7260 x19: ffff0000cfee7108 x18: ffff80009cba6e00
x17: 000000000000d2a0 x16: ffff8000832b5a70 x15: 0000000000000001
x14: 0000000000000000 x13: 0000000000000003 x12: ffff0000c2620000
x11: ffff800082da568c x10: 0000000000ff0100 x9 : 0000000000000000
x8 : 000000000000000d x7 : 0000000000000000 x6 : 0000000000000000
x5 : ffff800093813f70 x4 : 0000000000000002 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000000000005 x0 : ffff0000cfee7128
Call trace:
 efivarfs_pm_notify+0xcc/0x350 fs/efivarfs/super.c:480 (P)
 notifier_call_chain+0x1c4/0x550 kernel/notifier.c:85
 notifier_call_chain_robust kernel/notifier.c:120 [inline]
 blocking_notifier_call_chain_robust+0xdc/0x1bc kernel/notifier.c:345
 pm_notifier_call_chain_robust+0x34/0x64 kernel/power/main.c:102
 snapshot_open+0x11c/0x270 kernel/power/user.c:87
 misc_open+0x2b8/0x328 drivers/char/misc.c:179
 chrdev_open+0x3b0/0x4bc fs/char_dev.c:414
 do_dentry_open+0xb7c/0x1538 fs/open.c:956
 vfs_open+0x48/0x2d8 fs/open.c:1086
 do_open fs/namei.c:3830 [inline]
 path_openat+0x2308/0x2b1c fs/namei.c:3989
 do_filp_open+0x1e8/0x404 fs/namei.c:4016
 do_sys_openat2+0x124/0x1b8 fs/open.c:1428
 do_sys_open fs/open.c:1443 [inline]
 __do_sys_openat fs/open.c:1459 [inline]
 __se_sys_openat fs/open.c:1454 [inline]
 __arm64_sys_openat+0x1f0/0x240 fs/open.c:1454
 __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+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
Code: f940027c 9100a297 9101a398 d343ff08 (387a6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	f940027c 	ldr	x28, [x19]
   4:	9100a297 	add	x23, x20, #0x28
   8:	9101a398 	add	x24, x28, #0x68
   c:	d343ff08 	lsr	x8, x24, #3
* 10:	387a6908 	ldrb	w8, [x8, x26] <-- trapping instruction


---
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Re: [syzbot] [efi?] [fs?] BUG: unable to handle kernel paging request in efivarfs_pm_notify

[Ard Biesheuvel]

#syz test:
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci

--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -367,6 +367,8 @@ static int efivarfs_fill_super(struct super_block
*sb, struct fs_context *fc)
        if (err)
                return err;

+       register_pm_notifier(&sfi->pm_nb);
+
        return efivar_init(efivarfs_callback, sb, true);
 }

@@ -552,7 +554,6 @@ static int efivarfs_init_fs_context(struct fs_context *fc)

        sfi->pm_nb.notifier_call = efivarfs_pm_notify;
        sfi->pm_nb.priority = 0;
-       register_pm_notifier(&sfi->pm_nb);

        return 0;
 }

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

[Ard Biesheuvel]

#syz test:
git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi.git urgent

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

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to apply patch:
checking file fs/efivarfs/super.c
patch: **** unexpected end of file in patch



Tested on:

commit:         a1c24ab8 Merge branch 'for-next/el2-enable-feat-pmuv3p..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
kernel config:  https://syzkaller.appspot.com/x/.config?x=f6b108de97771157
dashboard link: https://syzkaller.appspot.com/bug?extid=00d13e505ef530a45100
compiler:       
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=17fe06e4580000

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

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+00d13e505ef530a45100@syzkaller.appspotmail.com
Tested-by: syzbot+00d13e505ef530a45100@syzkaller.appspotmail.com

Tested on:

commit:         ec7518a8 efivarfs: Defer PM notifier registration unti..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi.git urgent
console output: https://syzkaller.appspot.com/x/log.txt?x=15dfc7a4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3a97cba3fb7e034
dashboard link: https://syzkaller.appspot.com/bug?extid=00d13e505ef530a45100
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.