================================================================== BUG: KASAN: slab-out-of-bounds in string_nocheck lib/vsprintf.c:642 [inline] BUG: KASAN: slab-out-of-bounds in string+0x204/0x290 lib/vsprintf.c:724 Read of size 1 at addr ffff888054c3ba51 by task syz.6.352/5866 CPU: 1 PID: 5866 Comm: syz.6.352 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 print_address_description+0x60/0x2d0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:434 [inline] kasan_report+0xdf/0x130 mm/kasan/report.c:451 string_nocheck lib/vsprintf.c:642 [inline] string+0x204/0x290 lib/vsprintf.c:724 vsnprintf+0x10db/0x1c20 lib/vsprintf.c:2811 va_format lib/vsprintf.c:1713 [inline] pointer+0x7b2/0xc60 lib/vsprintf.c:2448 vsnprintf+0xd7c/0x1c20 lib/vsprintf.c:2815 vprintk_store+0x378/0x11b0 kernel/printk/printk.c:2164 vprintk_emit+0x85/0x150 kernel/printk/printk.c:2258 _printk+0xda/0x130 kernel/printk/printk.c:2299 __dynamic_pr_debug+0x196/0x240 lib/dynamic_debug.c:619 nfc_llcp_wks_sap net/nfc/llcp_core.c:344 [inline] nfc_llcp_get_sdp_ssap+0x3c1/0x3f0 net/nfc/llcp_core.c:420 llcp_sock_bind+0x3a2/0x770 net/nfc/llcp_sock.c:117 __sys_bind+0x2e9/0x3e0 net/socket.c:1730 __do_sys_bind net/socket.c:1741 [inline] __se_sys_bind net/socket.c:1739 [inline] __x64_sys_bind+0x76/0x80 net/socket.c:1739 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f5c5fff6159 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:00007f5c5e24e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000031 RAX: ffffffffffffffda RBX: 00007f5c6027dfa0 RCX: 00007f5c5fff6159 RDX: 0000000000000060 RSI: 0000200000000080 RDI: 0000000000000004 RBP: 00007f5c6008d06b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5c6027e038 R14: 00007f5c6027dfa0 R15: 00007fff4596ee68 Allocated by task 5866: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] __kasan_kmalloc+0xaf/0xe0 mm/kasan/common.c:522 kmemdup+0x22/0x50 mm/util.c:128 llcp_sock_bind+0x360/0x770 net/nfc/llcp_sock.c:107 __sys_bind+0x2e9/0x3e0 net/socket.c:1730 __do_sys_bind net/socket.c:1741 [inline] __se_sys_bind net/socket.c:1739 [inline] __x64_sys_bind+0x76/0x80 net/socket.c:1739 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 The buggy address belongs to the object at ffff888054c3ba50 which belongs to the cache kmalloc-8 of size 8 The buggy address is located 1 bytes inside of 8-byte region [ffff888054c3ba50, ffff888054c3ba58) The buggy address belongs to the page: page:ffffea0001530ec0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x54c3b flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 ffffea00007e5840 0000000900000009 ffff888016c41280 raw: 0000000000000000 0000000080660066 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 5074, ts 106348660676, free_ts 103718650789 prep_new_page mm/page_alloc.c:2426 [inline] get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501 alloc_slab_page mm/slub.c:1780 [inline] allocate_slab mm/slub.c:1917 [inline] new_slab+0xc0/0x4b0 mm/slub.c:1980 ___slab_alloc+0x807/0xdd0 mm/slub.c:3013 __slab_alloc mm/slub.c:3100 [inline] slab_alloc_node mm/slub.c:3191 [inline] slab_alloc mm/slub.c:3233 [inline] __kmalloc+0x11d/0x340 mm/slub.c:4408 kmalloc include/linux/slab.h:612 [inline] kernfs_fop_write_iter+0x14f/0x500 fs/kernfs/file.c:273 call_write_iter include/linux/fs.h:2179 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x748/0xd70 fs/read_write.c:594 ksys_write+0x153/0x260 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1340 [inline] free_pcp_prepare mm/page_alloc.c:1391 [inline] free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396 free_slab mm/slub.c:2020 [inline] discard_slab mm/slub.c:2026 [inline] __unfreeze_partials+0x188/0x1e0 mm/slub.c:2512 put_cpu_partial+0x12d/0x190 mm/slub.c:2592 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0x2f/0xc0 mm/kasan/common.c:444 kasan_slab_alloc include/linux/kasan.h:254 [inline] slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519 slab_alloc_node mm/slub.c:3225 [inline] kmem_cache_alloc_node+0x184/0x2c0 mm/slub.c:3261 __alloc_skb+0xf4/0x750 net/core/skbuff.c:415 alloc_skb include/linux/skbuff.h:1162 [inline] mld_newpack+0x12f/0xba0 net/ipv6/mcast.c:1773 add_grhead net/ipv6/mcast.c:1884 [inline] add_grec+0x1364/0x1840 net/ipv6/mcast.c:2023 mld_send_cr net/ipv6/mcast.c:2146 [inline] mld_ifc_work+0x6f2/0xd60 net/ipv6/mcast.c:2690 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/0x520 kernel/kthread.c:334 Memory state around the buggy address: ffff888054c3b900: fc fc 05 fc fc fc fc 05 fc fc fc fc 05 fc fc fc ffff888054c3b980: fc 05 fc fc fc fc 05 fc fc fc fc 05 fc fc fc fc >ffff888054c3ba00: 05 fc fc fc fc 05 fc fc fc fc 01 fc fc fc fc fb ^ ffff888054c3ba80: fc fc fc fc 05 fc fc fc fc 05 fc fc fc fc 05 fc ffff888054c3bb00: fc fc fc 05 fc fc fc fc 05 fc fc fc fc 05 fc fc ==================================================================