Re: [syzbot] [mm?] BUG: unable to handle kernel paging request in __pte_offset_map_lock

syzbot
2023-11-14T18:49:09Z

Hello,

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

Unable to handle kernel paging request at virtual address dfff800000000004
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
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
[dfff800000000004] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 7876 Comm: syz-executor.4 Not tainted 6.7.0-rc1-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
pstate: 804000c5 (Nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __lock_acquire+0x104/0x75e8 kernel/locking/lockdep.c:5004
lr : lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5753
sp : ffff800099b16d40
x29: ffff800099b17000 x28: ffff8000808f718c x27: ffff700013362e18
x26: 1ffff00011c62088 x25: 0000000000000000 x24: 0000000000000000
x23: ffff700013362dd0 x22: 0000000000000000 x21: 0000000000000000
x20: 0000000000000000 x19: 0000000000000022 x18: ffff800099b17750
x17: 0000000000000000 x16: ffff80008a7389ec x15: 0000000000000001
x14: ffff80008e310448 x13: ffff800099b16e80 x12: dfff800000000000
x11: ffff80008031ef10 x10: ffff80008e310444 x9 : 00000000000000f3
x8 : 0000000000000004 x7 : ffff8000808f718c x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000022
Call trace:
__lock_acquire+0x104/0x75e8 kernel/locking/lockdep.c:5004
lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5753
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x48/0x60 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
__pte_offset_map_lock+0x158/0x294 mm/pgtable-generic.c:375
pte_offset_map_lock include/linux/mm.h:2946 [inline]
filemap_map_pages+0x5cc/0x112c mm/filemap.c:3531
do_fault_around mm/memory.c:4586 [inline]
do_read_fault mm/memory.c:4619 [inline]
do_fault mm/memory.c:4762 [inline]
do_pte_missing mm/memory.c:3730 [inline]
handle_pte_fault mm/memory.c:5038 [inline]
__handle_mm_fault mm/memory.c:5179 [inline]
handle_mm_fault+0x35ec/0x49f8 mm/memory.c:5344
faultin_page mm/gup.c:956 [inline]
__get_user_pages+0x3e0/0xa24 mm/gup.c:1239
populate_vma_page_range+0x254/0x328 mm/gup.c:1677
__mm_populate+0x240/0x3d8 mm/gup.c:1786
mm_populate include/linux/mm.h:3379 [inline]
vm_mmap_pgoff+0x2bc/0x3d4 mm/util.c:551
ksys_mmap_pgoff+0xd0/0x5b0 mm/mmap.c:1425
__do_sys_mmap arch/arm64/kernel/sys.c:28 [inline]
__se_sys_mmap arch/arm64/kernel/sys.c:21 [inline]
__arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21
__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: 900704a8 b9424108 34000208 d343fe68 (386c6908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 900704a8 adrp x8, 0xe094000
4: b9424108 ldr w8, [x8, #576]
8: 34000208 cbz w8, 0x48
c: d343fe68 lsr x8, x19, #3
* 10: 386c6908 ldrb w8, [x8, x12] <-- trapping instruction

Tested on:

commit: b85ea95d Linux 6.7-rc1
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1052c057680000
kernel config: https://syzkaller.appspot.com/x/.config?x=fffc11e84313b7c6
dashboard link: https://syzkaller.appspot.com/bug?extid=89edd67979b52675ddec
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=1071c13f680000