================================================================== BUG: KASAN: slab-out-of-bounds in strnchr+0x5e/0x80 lib/string.c:405 Read of size 1 at addr ffff888034c55bb0 by task syz.0.28/6019 CPU: 0 UID: 0 PID: 6019 Comm: syz.0.28 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_sched_clock_irq+0xd3/0x1280 kernel/rcu/tree.c:2693 update_process_times+0x23c/0x2f0 kernel/time/timer.c:2474 tick_sched_handle kernel/time/tick-sched.c:298 [inline] tick_nohz_handler+0x3e9/0x710 kernel/time/tick-sched.c:319 __run_hrtimer kernel/time/hrtimer.c:1777 [inline] __hrtimer_run_queues+0x4d0/0xc30 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x102/0x3e0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0033:0x7f747038f749 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:00007fff5d1e1138 EFLAGS: 00000246 RAX: 0000000000000005 RBX: 00007f74705e5fa0 RCX: 00007f747038f749 RDX: 0000000000000018 RSI: 0000200000000180 RDI: 0000000000000011 RBP: 00007f7470413f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f74705e5fa0 R14: 00007f74705e5fa0 R15: 0000000000000003 Allocated by task 6019: 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 ffff888034c55800 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 [ffff888034c55800, ffff888034c55bb0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x34c50 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff88807650ea01 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88813ffb0280 ffffea0000c16200 dead000000000002 raw: 0000000000000000 0000000080100010 00000000f5000000 ffff88807650ea01 head: 00fff00000000040 ffff88813ffb0280 ffffea0000c16200 dead000000000002 head: 0000000000000000 0000000080100010 00000000f5000000 ffff88807650ea01 head: 00fff00000000003 ffffea0000d31401 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 0x252800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_THISNODE), pid 1, tgid 1 (swapper/0), ts 28012997339, free_ts 0 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_slab_page mm/slub.c:3077 [inline] allocate_slab+0x7a/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_noprof+0x5d9/0x820 mm/slub.c:5663 alloc_bulk+0x33b/0x530 kernel/bpf/memalloc.c:246 prefill_mem_cache kernel/bpf/memalloc.c:499 [inline] bpf_mem_alloc_init+0x9e9/0xc60 kernel/bpf/memalloc.c:569 bpf_global_ma_init+0x14/0x30 kernel/bpf/core.c:3264 do_one_initcall+0x1fb/0x820 init/main.c:1378 do_initcall_level+0x104/0x190 init/main.c:1440 do_initcalls+0x59/0xa0 init/main.c:1456 kernel_init_freeable+0x334/0x4b0 init/main.c:1688 kernel_init+0x1d/0x1d0 init/main.c:1578 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 page_owner free stack trace missing Memory state around the buggy address: ffff888034c55a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888034c55b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888034c55b80: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc ^ ffff888034c55c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888034c55c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================