syzbot


KASAN: slab-out-of-bounds Write in __bpf_get_stackid

Status: upstream: reported C repro on 2026/02/05 00:19
Bug presence: origin:lts
[Documentation on labels]
Reported-by: syzbot+6d2cdc0a08307ab5cc60@syzkaller.appspotmail.com
First crash: 1d20h, last: 1d18h
Bug presence (2)
Date Name Commit Repro Result
2026/02/05 lts (merge base) e50b81c50fcb C [report] KASAN: slab-out-of-bounds Write in __bpf_get_stackid
2026/02/05 upstream (ToT) f14faaf3a1fb C Didn't crash
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: slab-out-of-bounds Write in __bpf_get_stackid origin:lts-only 21 syz inconclusive 7 2d06h 178d 0/2 upstream: reported syz repro on 2025/08/11 20:18
upstream KASAN: slab-out-of-bounds Write in __bpf_get_stackid bpf 21 C error 170 98d 192d 29/29 fixed on 2026/01/07 12:29

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in __bpf_get_stackid+0x6fa/0x960 kernel/bpf/stackmap.c:274
Write of size 72 at addr ffff8881124d1610 by task syz.2.17/375

CPU: 1 PID: 375 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x71/0x200 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:420
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189
 memcpy+0x44/0x70 mm/kasan/shadow.c:66
 __bpf_get_stackid+0x6fa/0x960 kernel/bpf/stackmap.c:274
 ____bpf_get_stackid_pe kernel/bpf/stackmap.c:365 [inline]
 bpf_get_stackid_pe+0x2ee/0x400 kernel/bpf/stackmap.c:334
 bpf_prog_47e2b75ffb32ae9a+0x21/0x39
 bpf_dispatcher_nop_func include/linux/bpf.h:987 [inline]
 __bpf_prog_run include/linux/filter.h:607 [inline]
 bpf_prog_run include/linux/filter.h:614 [inline]
 bpf_overflow_handler+0x3d0/0x5e0 kernel/events/core.c:10238
 __perf_event_overflow+0x437/0x620 kernel/events/core.c:9448
 perf_swevent_overflow kernel/events/core.c:9524 [inline]
 perf_swevent_event+0x2f7/0x530 kernel/events/core.c:-1
 do_perf_sw_event kernel/events/core.c:9665 [inline]
 ___perf_sw_event+0x3bf/0x4f0 kernel/events/core.c:9696
 __perf_sw_event+0x134/0x270 kernel/events/core.c:9708
 perf_sw_event include/linux/perf_event.h:1250 [inline]
 do_user_addr_fault+0xffb/0x1050 arch/x86/mm/fault.c:1287
 handle_page_fault arch/x86/mm/fault.c:1466 [inline]
 exc_page_fault+0x51/0xb0 arch/x86/mm/fault.c:1522
 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:do_strncpy_from_user lib/strncpy_from_user.c:41 [inline]
RIP: 0010:strncpy_from_user+0xdf/0x2d0 lib/strncpy_from_user.c:139
Code: 00 00 4c 89 ee e8 e1 78 e2 fe 49 83 fd 07 0f 86 a2 00 00 00 4c 89 75 c0 49 c7 c7 f8 ff ff ff 45 31 e4 4c 89 65 c8 48 8b 45 c0 <4a> 8b 1c 20 48 b8 ff fe fe fe fe fe fe fe 4c 8d 34 03 49 89 dc 49
RSP: 0018:ffffc90000aa7cb8 EFLAGS: 00050246
RAX: 0000000000000000 RBX: 0000000000000fe0 RCX: ffff888113959440
RDX: 0000000000000000 RSI: 0000000000000fe0 RDI: 0000000000000007
RBP: ffffc90000aa7d00 R08: ffffea0004530407 R09: 1ffffd40008a6080
R10: dffffc0000000000 R11: fffff940008a6081 R12: 0000000000000000
R13: 0000000000000fe0 R14: 0000000000000000 R15: fffffffffffffff8
 getname_flags+0xf4/0x500 fs/namei.c:150
 getname+0x19/0x20 fs/namei.c:218
 do_sys_openat2+0xeb/0x810 fs/open.c:1337
 do_sys_open fs/open.c:1359 [inline]
 __do_sys_openat fs/open.c:1375 [inline]
 __se_sys_openat fs/open.c:1370 [inline]
 __x64_sys_openat+0x136/0x160 fs/open.c:1370
 x64_sys_call+0x783/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3c2119aeb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc2ac4c058 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f3c21415fa0 RCX: 00007f3c2119aeb9
RDX: 00000000000026e1 RSI: 0000000000000000 RDI: ffffffffffffff9c
RBP: 00007f3c21208c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3c21415fac R14: 00007f3c21415fa0 R15: 00007f3c21415fa0
 </TASK>

Allocated by task 375:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:380 [inline]
 __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
 kasan_kmalloc include/linux/kasan.h:212 [inline]
 __do_kmalloc_node mm/slab_common.c:938 [inline]
 __kmalloc_node+0xb2/0x1e0 mm/slab_common.c:945
 kmalloc_node include/linux/slab.h:589 [inline]
 __bpf_map_area_alloc kernel/bpf/syscall.c:328 [inline]
 bpf_map_area_alloc+0x4b/0xe0 kernel/bpf/syscall.c:341
 prealloc_elems_and_freelist+0x8a/0x1e0 kernel/bpf/stackmap.c:51
 stack_map_alloc+0x3a7/0x530 kernel/bpf/stackmap.c:117
 find_and_alloc_map kernel/bpf/syscall.c:133 [inline]
 map_create+0x49c/0xd80 kernel/bpf/syscall.c:1126
 __sys_bpf+0x34e/0x850 kernel/bpf/syscall.c:4987
 __do_sys_bpf kernel/bpf/syscall.c:5109 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5107 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5107
 x64_sys_call+0x488/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff8881124d1600
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 16 bytes inside of
 64-byte region [ffff8881124d1600, ffff8881124d1640)

The buggy address belongs to the physical page:
page:ffffea0004493440 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1124d1
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 0000000000000000 dead000000000001 ffff888100042780
raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 100, tgid 100 (S10udev), ts 5068578988, free_ts 0
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2643
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2650
 get_page_from_freelist+0x2d12/0x2d80 mm/page_alloc.c:4554
 __alloc_pages+0x1d9/0x480 mm/page_alloc.c:5868
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3d0 mm/slub.c:2020
 ___slab_alloc+0x6bd/0xb20 mm/slub.c:3177
 __slab_alloc+0x5e/0xa0 mm/slub.c:3263
 slab_alloc_node mm/slub.c:3348 [inline]
 __kmem_cache_alloc_node+0x203/0x2c0 mm/slub.c:3423
 kmalloc_trace+0x29/0xb0 mm/slab_common.c:1028
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 alloc_task_dma_buf_info drivers/dma-buf/dma-buf.c:502 [inline]
 dup_dma_buf_info drivers/dma-buf/dma-buf.c:521 [inline]
 copy_dmabuf_info+0x35d/0xf50 drivers/dma-buf/dma-buf.c:638
 copy_process+0x1b32/0x3510 kernel/fork.c:2564
 kernel_clone+0x22f/0x820 kernel/fork.c:2890
 __do_sys_clone kernel/fork.c:3033 [inline]
 __se_sys_clone kernel/fork.c:3017 [inline]
 __x64_sys_clone+0x193/0x200 kernel/fork.c:3017
 x64_sys_call+0x990/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881124d1500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8881124d1580: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff8881124d1600: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
                                  ^
 ffff8881124d1680: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8881124d1700: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	4c 89 ee             	mov    %r13,%rsi
   5:	e8 e1 78 e2 fe       	call   0xfee278eb
   a:	49 83 fd 07          	cmp    $0x7,%r13
   e:	0f 86 a2 00 00 00    	jbe    0xb6
  14:	4c 89 75 c0          	mov    %r14,-0x40(%rbp)
  18:	49 c7 c7 f8 ff ff ff 	mov    $0xfffffffffffffff8,%r15
  1f:	45 31 e4             	xor    %r12d,%r12d
  22:	4c 89 65 c8          	mov    %r12,-0x38(%rbp)
  26:	48 8b 45 c0          	mov    -0x40(%rbp),%rax
* 2a:	4a 8b 1c 20          	mov    (%rax,%r12,1),%rbx <-- trapping instruction
  2e:	48 b8 ff fe fe fe fe 	movabs $0xfefefefefefefeff,%rax
  35:	fe fe fe
  38:	4c 8d 34 03          	lea    (%rbx,%rax,1),%r14
  3c:	49 89 dc             	mov    %rbx,%r12
  3f:	49                   	rex.WB

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/05 01:30 android14-6.1 775f23d50ca8 ea10c935 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-1-perf KASAN: slab-out-of-bounds Write in __bpf_get_stackid
2026/02/05 00:50 android14-6.1 775f23d50ca8 ea10c935 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-1-perf KASAN: slab-out-of-bounds Write in __bpf_get_stackid
2026/02/05 00:08 android14-6.1 775f23d50ca8 ea10c935 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-1-perf KASAN: slab-out-of-bounds Write in __bpf_get_stackid
2026/02/04 23:25 android14-6.1 775f23d50ca8 ea10c935 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1-perf KASAN: slab-out-of-bounds Write in __bpf_get_stackid
* Struck through repros no longer work on HEAD.