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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aafe7ad77b91 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=13836436e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=23ce86eb3d78ef4d
dashboard link: https://syzkaller.appspot.com/bug?extid=0e7b9b7452ded0356f2d
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=169f2595e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12ef73d6e80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/23845238c49b/disk-aafe7ad7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1144b0f74104/vmlinux-aafe7ad7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6db20df213a2/Image-aafe7ad7.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0e7b9b...@syzkaller.appspotmail.com

Unable to handle kernel paging request at virtual address dfff8000000000d1
KASAN: null-ptr-deref in range [0x0000000000000688-0x000000000000068f]
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
[dfff8000000000d1] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 6095 Comm: syz-executor387 Not tainted 6.7.0-rc6-syzkaller-gaafe7ad77b91 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : mm_has_notifiers include/linux/mmu_notifier.h:282 [inline]
pc : mmu_notifier_invalidate_range_start+0x80/0x10c include/linux/mmu_notifier.h:455
lr : mmu_notifier_invalidate_range_start+0x60/0x10c include/linux/mmu_notifier.h:454
sp : ffff800096d97a10
x29: ffff800096d97a10 x28: ffff800096d97be0 x27: ffff800096d97bb8
x26: 0000000020ffc000 x25: ffff700012db2f68 x24: 1ffff00012db2f78
x23: dfff800000000000 x22: ffff0000da811e00 x21: dfff800000000000
x20: 0000000000000688 x19: ffff800096d97b60 x18: 0000000000000000
x17: 00000000c0606610 x16: ffff80008a82b25c x15: 0000000020000180
x14: ffff80008e4f0448 x13: dfff800000000000 x12: 00000000050405e5
x11: 00000000d5d3f9bd x10: 0000000000ff0100 x9 : 343472906370af00
x8 : 00000000000000d1 x7 : ffff800080cc5610 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000008 x1 : 0000000000000080 x0 : 0000000000000001
Call trace:
mm_has_notifiers include/linux/mmu_notifier.h:282 [inline]
mmu_notifier_invalidate_range_start+0x80/0x10c include/linux/mmu_notifier.h:455
do_pagemap_scan fs/proc/task_mmu.c:2438 [inline]
do_pagemap_cmd+0x880/0x11ec fs/proc/task_mmu.c:2494
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl fs/ioctl.c:857 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x54/0x158 arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595
Code: 97f46443 f9400268 911a2114 d343fe88 (38756908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 97f46443 bl 0xffffffffffd1910c
4: f9400268 ldr x8, [x19]
8: 911a2114 add x20, x8, #0x688
c: d343fe88 lsr x8, x20, #3
* 10: 38756908 ldrb w8, [x8, x21] <-- trapping instruction


---
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[Hillf Danton]

On Fri, 29 Dec 2023 11:44:19 -0800

> HEAD commit: aafe7ad77b91 Merge branch 'for-next/core' into for-kernelci
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12ef73d6e80000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

--- x/fs/proc/task_mmu.c
+++ y/fs/proc/task_mmu.c
@@ -2491,8 +2491,9 @@ static long do_pagemap_cmd(struct file *

switch (cmd) {
case PAGEMAP_SCAN:
- return do_pagemap_scan(mm, arg);
-
+ if (mm)
+ return do_pagemap_scan(mm, arg);
+ /* fall thru */
default:
return -EINVAL;
}
--

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+0e7b9b...@syzkaller.appspotmail.com

Tested on:

commit: f016f754 Merge tag 'gpio-fixes-for-v6.7-rc8' of git://..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=115dfc65e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=57ef848c54f4cb25

dashboard link: https://syzkaller.appspot.com/bug?extid=0e7b9b7452ded0356f2d
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

patch: https://syzkaller.appspot.com/x/patch.diff?x=12f5f4b1e80000

Note: testing is done by a robot and is best-effort only.

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.