syzbot
UBSAN: array-index-out-of-bounds in copy_fs_struct
Status:
premoderation: reported syz repro on 2026/10/09 00:16
Reported-by: syzbot+c05a419756779fe2463c@syzkaller.appspotmail.com
First crash: 1d05h, last: 1d05h
Sample crash report:
================================================================================
UBSAN: array-index-out-of-bounds in kernel/locking/qspinlock.c:130:9
index 6482 is out of range for type 'unsigned long[8]'
CPU: 1 PID: 373 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
__dump_stack+0x21/0x24 lib/dump_stack.c:77
dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
dump_stack+0x15/0x1c lib/dump_stack.c:135
ubsan_epilogue+0xe/0x40 lib/ubsan.c:148
__ubsan_handle_out_of_bounds+0xdf/0xf0 lib/ubsan.c:347
decode_tail kernel/locking/qspinlock.c:130 [inline]
__pv_queued_spin_lock_slowpath+0xb03/0xb80 kernel/locking/qspinlock.c:468
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:554 [inline]
queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51
queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
do_raw_spin_lock include/linux/spinlock.h:184 [inline]
__raw_spin_lock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_lock+0xe4/0xf0 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:355 [inline]
get_partial_node mm/slub.c:2020 [inline]
get_partial mm/slub.c:2125 [inline]
new_slab_objects mm/slub.c:2627 [inline]
___slab_alloc+0x110/0x4c0 mm/slub.c:2796
__slab_alloc+0x63/0xa0 mm/slub.c:2836
slab_alloc_node mm/slub.c:2918 [inline]
slab_alloc mm/slub.c:2960 [inline]
kmem_cache_alloc+0x1a4/0x2d0 mm/slub.c:2965
copy_fs_struct+0x4c/0x220 fs/fs_struct.c:115
copy_fs+0x6f/0x140 kernel/fork.c:1518
copy_process+0x1302/0x3320 kernel/fork.c:2259
kernel_clone+0x233/0x950 kernel/fork.c:2650
__do_sys_clone kernel/fork.c:2776 [inline]
__se_sys_clone kernel/fork.c:2760 [inline]
__x64_sys_clone+0x198/0x210 kernel/fork.c:2760
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f89813a5c52
Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00
RSP: 002b:00007fffb5e5fea0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007fffb5e5fea0 RCX: 00007f89813a5c52
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007fffb5e6002c R08: 0000000000000000 R09: 0000000000000001
R10: 00005555937cf7d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000927c0 R14: 0000000000006848 R15: 00007fffb5e60080
================================================================================
general protection fault, probably for non-canonical address 0xff6cc73b9f6d798a: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range [0xfb6659dcfb6bcc50-0xfb6659dcfb6bcc57]
CPU: 1 PID: 373 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:__pv_queued_spin_lock_slowpath+0x2cc/0xb80 kernel/locking/qspinlock.c:471
Code: 74 14 48 89 54 24 18 48 8b 7c 24 18 e8 1d 55 53 00 48 8b 54 24 18 4c 03 2a 4c 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ef e8 96 55 53 00 48 8b 44 24 40 49 89 45
RSP: 0018:ffffc90000cf7800 EFLAGS: 00010803
RAX: 1f6ccb3b9f6d798a RBX: ffff88810006c000 RCX: dffffc0000000000
RDX: ffffffff85c01150 RSI: 0000000000000001 RDI: 00000000ffffffff
RBP: ffffc90000cf78f0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff0dcf848 R12: 1ffff1103ee2ae51
R13: fb6659dcfb6bcc56 R14: 1ffff1102000d800 R15: ffff8881f7157294
FS: 00005555937cf500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f89821346c8 CR3: 000000010bfbd000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:554 [inline]
queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51
queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
do_raw_spin_lock include/linux/spinlock.h:184 [inline]
__raw_spin_lock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_lock+0xe4/0xf0 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:355 [inline]
get_partial_node mm/slub.c:2020 [inline]
get_partial mm/slub.c:2125 [inline]
new_slab_objects mm/slub.c:2627 [inline]
___slab_alloc+0x110/0x4c0 mm/slub.c:2796
__slab_alloc+0x63/0xa0 mm/slub.c:2836
slab_alloc_node mm/slub.c:2918 [inline]
slab_alloc mm/slub.c:2960 [inline]
kmem_cache_alloc+0x1a4/0x2d0 mm/slub.c:2965
copy_fs_struct+0x4c/0x220 fs/fs_struct.c:115
copy_fs+0x6f/0x140 kernel/fork.c:1518
copy_process+0x1302/0x3320 kernel/fork.c:2259
kernel_clone+0x233/0x950 kernel/fork.c:2650
__do_sys_clone kernel/fork.c:2776 [inline]
__se_sys_clone kernel/fork.c:2760 [inline]
__x64_sys_clone+0x198/0x210 kernel/fork.c:2760
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f89813a5c52
Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00
RSP: 002b:00007fffb5e5fea0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007fffb5e5fea0 RCX: 00007f89813a5c52
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007fffb5e6002c R08: 0000000000000000 R09: 0000000000000001
R10: 00005555937cf7d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000927c0 R14: 0000000000006848 R15: 00007fffb5e60080
Modules linked in:
---[ end trace eacec6d22677ab92 ]---
RIP: 0010:__pv_queued_spin_lock_slowpath+0x2cc/0xb80 kernel/locking/qspinlock.c:471
Code: 74 14 48 89 54 24 18 48 8b 7c 24 18 e8 1d 55 53 00 48 8b 54 24 18 4c 03 2a 4c 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ef e8 96 55 53 00 48 8b 44 24 40 49 89 45
RSP: 0018:ffffc90000cf7800 EFLAGS: 00010803
RAX: 1f6ccb3b9f6d798a RBX: ffff88810006c000 RCX: dffffc0000000000
RDX: ffffffff85c01150 RSI: 0000000000000001 RDI: 00000000ffffffff
RBP: ffffc90000cf78f0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff0dcf848 R12: 1ffff1103ee2ae51
R13: fb6659dcfb6bcc56 R14: 1ffff1102000d800 R15: ffff8881f7157294
FS: 00005555937cf500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f89821346c8 CR3: 000000010bfbd000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 74 14 je 0x16
2: 48 89 54 24 18 mov %rdx,0x18(%rsp)
7: 48 8b 7c 24 18 mov 0x18(%rsp),%rdi
c: e8 1d 55 53 00 call 0x53552e
11: 48 8b 54 24 18 mov 0x18(%rsp),%rdx
16: 4c 03 2a add (%rdx),%r13
19: 4c 89 e8 mov %r13,%rax
1c: 48 c1 e8 03 shr $0x3,%rax
20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
27: fc ff df
* 2a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 ef mov %r13,%rdi
33: e8 96 55 53 00 call 0x5355ce
38: 48 8b 44 24 40 mov 0x40(%rsp),%rax
3d: 49 rex.WB
3e: 89 .byte 0x89
3f: 45 rex.RB
Struck through repros no longer work on HEAD.