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

[syzbot]

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: 0 PID: 6731 Comm: syz-executor.5 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 : ffff800097066d40
x29: ffff800097067000 x28: ffff8000808f70ac x27: ffff700012e0ce18
x26: 1ffff00011c64088 x25: 0000000000000000 x24: 0000000000000000
x23: ffff700012e0cdd0 x22: 0000000000000000 x21: 0000000000000000
x20: 0000000000000000 x19: 0000000000000022 x18: ffff800097067750
x17: ffff80008e31d000 x16: ffff80008a73b6ac x15: 0000000000000001
x14: ffff80008e320448 x13: ffff800097066e80 x12: dfff800000000000
x11: ffff80008031ef10 x10: ffff80008e320444 x9 : 00000000000000f3
x8 : 0000000000000004 x7 : ffff8000808f70ac 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+0x154/0x360 mm/pgtable-generic.c:378
 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:4588 [inline]
 do_read_fault mm/memory.c:4621 [inline]
 do_fault mm/memory.c:4764 [inline]
 do_pte_missing mm/memory.c:3732 [inline]
 handle_pte_fault mm/memory.c:5040 [inline]
 __handle_mm_fault mm/memory.c:5181 [inline]
 handle_mm_fault+0x35ec/0x49f8 mm/memory.c:5346
 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: 90070528 b9424108 34000208 d343fe68 (386c6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	90070528 	adrp	x8, 0xe0a4000
   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=14cf3388e80000
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=136db347680000