syzbot


BUG: unable to handle kernel NULL pointer dereference in alloc_pid

Status: moderation: reported on 2025/04/18 03:35
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+c9fd1f3d275971dbb9eb@syzkaller.appspotmail.com
First crash: 33d, last: 33d

Sample crash report:
F2FS-fs (loop1): Can't find valid F2FS filesystem in 1th superblock
F2FS-fs (loop1): Try to recover 1th superblock, ret: 0
F2FS-fs (loop1): Mounted with checkpoint version = 48b305e5
Unable to handle kernel NULL pointer dereference at virtual address 000000000000000a
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=00000001116b0000
[000000000000000a] pgd=080000012d459403, p4d=080000012d459403, pud=080000010f113403, pmd=0000000000000000
Internal error: Oops: 0000000096000006 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 6908 Comm: syz.1.125 Not tainted 6.15.0-rc1-syzkaller-g2fe2b96c3818 #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : const_folio_flags include/linux/page-flags.h:347 [inline]
pc : folio_test_active include/linux/page-flags.h:556 [inline]
pc : slab_test_pfmemalloc mm/slab.h:176 [inline]
pc : pfmemalloc_match mm/slub.c:3594 [inline]
pc : ___slab_alloc+0x27c/0xf4c mm/slub.c:3735
lr : __slab_alloc+0x74/0xd0 mm/slub.c:3952
sp : ffff80009d767660
x29: ffff80009d7676c0 x28: dfff800000000000 x27: 0000000000000cc0
x26: 0000000000000002 x25: 00000000ffffffff x24: 00007dfe9be821e0
x23: 0000000000000002 x22: ffff80008038f89c x21: ffff800097bc0988
x20: fffffdffbf7071e0 x19: ffff0000c5facdc0 x18: 1ffff00013aeceb0
x17: ffff8000802f51ac x16: ffff8000833376cc x15: 0000000000000003
x14: 0000000000000000 x13: 000000000000008f x12: 000000000000008f
x11: 0000000000080000 x10: 0000000000000003 x9 : ffff80008ff41de8
x8 : fc9d45adb9581200 x7 : ffff800080b53c40 x6 : 0000000000000000
x5 : 0000000000000128 x4 : fffffdffbf7071e0 x3 : ffff80008038f89c
x2 : 00000000ffffffff x1 : 0000000000000cc0 x0 : ffff0000c5facdc0
Call trace:
 ___slab_alloc+0x27c/0xf4c mm/slub.c:-1 (P)
 __slab_alloc+0x74/0xd0 mm/slub.c:3952
 __slab_alloc_node mm/slub.c:4027 [inline]
 slab_alloc_node mm/slub.c:4188 [inline]
 kmem_cache_alloc_noprof+0x300/0x410 mm/slub.c:4207
 alloc_pid+0xac/0xba8 kernel/pid.c:182
 copy_process+0x1a4c/0x3230 kernel/fork.c:2445
 kernel_clone+0x1d8/0x82c kernel/fork.c:2844
 __do_sys_clone kernel/fork.c:2987 [inline]
 __se_sys_clone kernel/fork.c:2955 [inline]
 __arm64_sys_clone+0x1f8/0x270 kernel/fork.c:2955
 __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: aa1703e1 94a7fa12 17ffffe3 12800019 (394022e8) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	aa1703e1 	mov	x1, x23
   4:	94a7fa12 	bl	0x29fe84c
   8:	17ffffe3 	b	0xffffffffffffff94
   c:	12800019 	mov	w25, #0xffffffff            	// #-1
* 10:	394022e8 	ldrb	w8, [x23, #8] <-- trapping instruction

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/14 03:32 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 2fe2b96c3818 0bd6db41 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: unable to handle kernel NULL pointer dereference in alloc_pid
* Struck through repros no longer work on HEAD.