KASAN: slab-out-of-bounds Read in strnchr

Title	Replies (including bot)	Last reply
[PATCH] bpf: Format string can't be empty	4 (4)	2026/01/08 21:43
[PATCH] bpf: Reject BPF_MAP_TYPE_INSN_ARRAY in check_reg_const_str()	3 (3)	2026/01/08 03:10
[syzbot] [bpf?] KASAN: slab-out-of-bounds Read in strnchr	1 (6)	2026/01/07 09:39

Title

Replies (including bot)

Last reply

[PATCH] bpf: Format string can't be empty

4 (4)

2026/01/08 21:43

[PATCH] bpf: Reject BPF_MAP_TYPE_INSN_ARRAY in check_reg_const_str()

3 (3)

2026/01/08 03:10

[syzbot] [bpf?] KASAN: slab-out-of-bounds Read in strnchr

1 (6)

2026/01/07 09:39

Kernel	Title	Rank 🛈	Repro	Cause bisect	Count	Last	Reported	Patched	Status
upstream	KMSAN: uninit-value in strnchr (2) bpf	7	C		80	578d	580d	0/29	auto-obsoleted due to no activity on 2024/09/05 01:35
upstream	KMSAN: uninit-value in strnchr bpf	7	C		173	585d	675d	0/29	closed as dup on 2024/04/09 05:30
upstream	KMSAN: uninit-value in ieee802154_subif_start_xmit bpf	8	C	done	119	893d	889d	23/29	fixed on 2023/10/12 12:47

Rank 🛈

upstream

KMSAN: uninit-value in strnchr (2) bpf

578d

580d

0/29

auto-obsoleted due to no activity on 2024/09/05 01:35

upstream

KMSAN: uninit-value in strnchr bpf

173

585d

675d

0/29

closed as dup on 2024/04/09 05:30

upstream

KMSAN: uninit-value in ieee802154_subif_start_xmit bpf

done

119

893d

889d

23/29

fixed on 2023/10/12 12:47


Created	Duration	User	Patch	Repo	Result
2026/01/07 08:47	35m	eadavis@qq.com	patch	bpf	OK log
2026/01/06 15:44	54m	kartikey406@gmail.com	patch	bpf	OK log
2026/01/06 05:19	1h02m	kartikey406@gmail.com	patch	bpf	report log
2026/01/06 04:48	23m	kartikey406@gmail.com	patch	bpf	report log

================================================================== BUG: KASAN: slab-out-of-bounds in strnchr+0x5e/0x80 lib/string.c:405 Read of size 1 at addr ffff888029e093b0 by task ksoftirqd/1/23 CPU: 1 UID: 0 PID: 23 Comm: ksoftirqd/1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: <TASK> dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 strnchr+0x5e/0x80 lib/string.c:405 bpf_bprintf_prepare+0x167/0x13d0 kernel/bpf/helpers.c:829 ____bpf_snprintf kernel/bpf/helpers.c:1065 [inline] bpf_snprintf+0xd3/0x1b0 kernel/bpf/helpers.c:1049 bpf_prog_c2925c0a7ac12d80+0x58/0x60 bpf_dispatcher_nop_func include/linux/bpf.h:1378 [inline] __bpf_prog_run include/linux/filter.h:723 [inline] bpf_prog_run include/linux/filter.h:730 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2075 [inline] bpf_trace_run1+0x27f/0x4c0 kernel/trace/bpf_trace.c:2115 __bpf_trace_rcu_utilization+0xa1/0xf0 include/trace/events/rcu.h:27 __do_trace_rcu_utilization include/trace/events/rcu.h:27 [inline] trace_rcu_utilization+0x191/0x1c0 include/trace/events/rcu.h:27 rcu_core+0x13fe/0x1870 kernel/rcu/tree.c:2865 handle_softirqs+0x27d/0x850 kernel/softirq.c:622 run_ksoftirqd+0x9b/0x100 kernel/softirq.c:1063 smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 </TASK> Allocated by task 6022: kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 poison_kmalloc_redzone mm/kasan/common.c:397 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:414 kasan_kmalloc include/linux/kasan.h:262 [inline] __do_kmalloc_node mm/slub.c:5657 [inline] __kmalloc_node_noprof+0x57a/0x820 mm/slub.c:5663 kmalloc_node_noprof include/linux/slab.h:987 [inline] __bpf_map_area_alloc kernel/bpf/syscall.c:395 [inline] bpf_map_area_alloc+0x64/0x180 kernel/bpf/syscall.c:408 insn_array_alloc+0x52/0x140 kernel/bpf/bpf_insn_array.c:49 map_create+0xafd/0x16a0 kernel/bpf/syscall.c:1514 __sys_bpf+0x5f0/0x860 kernel/bpf/syscall.c:6146 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline] __se_sys_bpf kernel/bpf/syscall.c:6272 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6272 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888029e09000 which belongs to the cache kmalloc-cg-1k of size 1024 The buggy address is located 0 bytes to the right of allocated 944-byte region [ffff888029e09000, ffff888029e093b0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29e08 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff888072141701 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88813ffb0280 dead000000000100 dead000000000122 raw: 0000000000000000 0000000080100010 00000000f5000000 ffff888072141701 head: 00fff00000000040 ffff88813ffb0280 dead000000000100 dead000000000122 head: 0000000000000000 0000000080100010 00000000f5000000 ffff888072141701 head: 00fff00000000003 ffffea0000a78201 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5709, tgid 5709 (dhcpcd-run-hook), ts 83835394493, free_ts 83796353079 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x234/0x290 mm/page_alloc.c:1846 prep_new_page mm/page_alloc.c:1854 [inline] get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3915 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486 alloc_slab_page mm/slub.c:3075 [inline] allocate_slab+0x86/0x3b0 mm/slub.c:3248 new_slab mm/slub.c:3302 [inline] ___slab_alloc+0xf2b/0x1960 mm/slub.c:4656 __slab_alloc+0x65/0x100 mm/slub.c:4779 __slab_alloc_node mm/slub.c:4855 [inline] slab_alloc_node mm/slub.c:5251 [inline] __do_kmalloc_node mm/slub.c:5656 [inline] __kmalloc_noprof+0x47d/0x800 mm/slub.c:5669 kmalloc_noprof include/linux/slab.h:961 [inline] kmalloc_array_noprof include/linux/slab.h:1003 [inline] alloc_pipe_info+0x1fd/0x4d0 fs/pipe.c:817 get_pipe_inode fs/pipe.c:896 [inline] create_pipe_files+0x8a/0x7e0 fs/pipe.c:928 __do_pipe_flags+0x46/0x1f0 fs/pipe.c:990 do_pipe2+0x9c/0x170 fs/pipe.c:1038 __do_sys_pipe2 fs/pipe.c:1056 [inline] __se_sys_pipe2 fs/pipe.c:1054 [inline] __x64_sys_pipe2+0x5a/0x70 fs/pipe.c:1054 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 5712 tgid 5712 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1395 [inline] __free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2943 __slab_free+0x21b/0x2a0 mm/slub.c:6004 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:349 kasan_slab_alloc include/linux/kasan.h:252 [inline] slab_post_alloc_hook mm/slub.c:4953 [inline] slab_alloc_node mm/slub.c:5263 [inline] kmem_cache_alloc_noprof+0x37d/0x710 mm/slub.c:5270 vm_area_alloc+0x24/0x140 mm/vma_init.c:32 __mmap_new_vma mm/vma.c:2469 [inline] __mmap_region mm/vma.c:2708 [inline] mmap_region+0xdea/0x1d10 mm/vma.c:2786 do_mmap+0xc45/0x10d0 mm/mmap.c:558 vm_mmap_pgoff+0x2a6/0x4d0 mm/util.c:581 ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:604 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff888029e09280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888029e09300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888029e09380: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc ^ ffff888029e09400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888029e09480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================

Crashes (14):
Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Assets (help?)	Manager	Title
2026/01/03 03:34	bpf	22cc16c04b78	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 18:52	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 17:22	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 15:53	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 14:26	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 12:53	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 11:29	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 09:58	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 08:38	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 07:21	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 06:05	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report	syz / log	C		[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/10 22:38	net-next	959728f9931e	d6526ea3	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-net-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 03:17	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr
2026/01/02 03:17	bpf-next	c286e7e9d1f1	d6526ea3	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-bpf-next-kasan-gce	KASAN: slab-out-of-bounds Read in strnchr

Crashes (14):

Assets (help?)