================================================================== BUG: KASAN: slab-out-of-bounds in strnchr+0x5e/0x80 lib/string.c:405 Read of size 1 at addr ffff888030a503b0 by task syz.0.17/5992 CPU: 0 UID: 0 PID: 5992 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: 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:1394 [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_note_context_switch+0xc9/0x1120 kernel/rcu/tree_plugin.h:330 __schedule+0x346/0x5000 kernel/sched/core.c:6748 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7047 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7071 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __local_bh_enable_ip+0x13e/0x1c0 kernel/softirq.c:457 spin_unlock_bh include/linux/spinlock.h:396 [inline] bpf_link_free_id kernel/bpf/syscall.c:3218 [inline] bpf_link_free+0x9e/0x330 kernel/bpf/syscall.c:3276 bpf_link_put_direct kernel/bpf/syscall.c:3322 [inline] bpf_link_release+0x6b/0x80 kernel/bpf/syscall.c:3329 __fput+0x44c/0xa70 fs/file_table.c:468 task_work_run+0x1d4/0x260 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:44 [inline] exit_to_user_mode_loop+0xff/0x4f0 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2d0/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0feaf8f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd5bd92a08 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 000000000001b1e0 RCX: 00007f0feaf8f749 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000001 R09: 000000045bd92cff R10: 0000001b2f620000 R11: 0000000000000246 R12: 00007f0feb1e5fac R13: 00007f0feb1e5fa0 R14: ffffffffffffffff R15: 0000000000000003 Allocated by task 5992: 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+0x682/0x8a0 kernel/bpf/syscall.c:6189 __do_sys_bpf kernel/bpf/syscall.c:6320 [inline] __se_sys_bpf kernel/bpf/syscall.c:6318 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6318 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 ffff888030a50000 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 [ffff888030a50000, ffff888030a503b0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x30a50 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff8880765c5001 anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88813ffb0280 0000000000000000 0000000000000001 raw: 0000000000000000 0000000080100010 00000000f5000000 ffff8880765c5001 head: 00fff00000000040 ffff88813ffb0280 0000000000000000 0000000000000001 head: 0000000000000000 0000000080100010 00000000f5000000 ffff8880765c5001 head: 00fff00000000003 ffffea0000c29401 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 5492, tgid 5492 (dhcpcd), ts 78008527365, free_ts 77923391814 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_node_track_caller_noprof+0x5d4/0x820 mm/slub.c:5764 kmalloc_reserve+0x136/0x290 net/core/skbuff.c:608 __alloc_skb+0x27e/0x430 net/core/skbuff.c:690 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6712 sock_alloc_send_pskb+0x84d/0x980 net/core/sock.c:2995 unix_dgram_sendmsg+0x454/0x1840 net/unix/af_unix.c:2130 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:742 sock_write_iter+0x279/0x360 net/socket.c:1195 do_iter_readv_writev+0x623/0x8c0 fs/read_write.c:-1 page last free pid 5780 tgid 5780 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 discard_slab mm/slub.c:3346 [inline] __put_partials+0x146/0x170 mm/slub.c:3886 put_cpu_partial+0x1f2/0x2d0 mm/slub.c:3961 __slab_free+0x288/0x2a0 mm/slub.c:5952 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_node_noprof+0x43c/0x720 mm/slub.c:5315 alloc_task_struct_node kernel/fork.c:184 [inline] dup_task_struct+0x57/0x9a0 kernel/fork.c:915 copy_process+0x4ea/0x3950 kernel/fork.c:2052 kernel_clone+0x21e/0x820 kernel/fork.c:2651 __do_sys_clone kernel/fork.c:2792 [inline] __se_sys_clone kernel/fork.c:2776 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2776 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: ffff888030a50280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888030a50300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888030a50380: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc ^ ffff888030a50400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888030a50480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================