================================================================== BUG: KASAN: use-after-free in string_nocheck lib/vsprintf.c:641 [inline] BUG: KASAN: use-after-free in string+0x21f/0x2b0 lib/vsprintf.c:723 Read of size 1 at addr ffff88810e943cb9 by task syz.5.1076/4015 CPU: 1 PID: 4015 Comm: syz.5.1076 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2025 Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:77 dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:435 [inline] kasan_report+0xe2/0x130 mm/kasan/report.c:452 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:306 string_nocheck lib/vsprintf.c:641 [inline] string+0x21f/0x2b0 lib/vsprintf.c:723 vsnprintf+0xf20/0x1960 lib/vsprintf.c:2689 seq_vprintf fs/seq_file.c:398 [inline] seq_printf+0x175/0x260 fs/seq_file.c:413 input_devices_seq_show+0x1a6/0x650 drivers/input/input.c:1186 seq_read_iter+0x93f/0xd30 fs/seq_file.c:272 seq_read+0x3cc/0x4d0 fs/seq_file.c:162 pde_read fs/proc/inode.c:321 [inline] proc_reg_read+0x1c4/0x2b0 fs/proc/inode.c:333 vfs_read+0x1fe/0xa10 fs/read_write.c:494 ksys_read+0x140/0x240 fs/read_write.c:634 __do_sys_read fs/read_write.c:644 [inline] __se_sys_read fs/read_write.c:642 [inline] __x64_sys_read+0x7b/0x90 fs/read_write.c:642 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7fb7885efc29 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:00007fb787016038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007fb788837180 RCX: 00007fb7885efc29 RDX: 0000000000002020 RSI: 0000200000000300 RDI: 0000000000000007 RBP: 00007fb788672e41 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb788837218 R14: 00007fb788837180 R15: 00007ffe7f9e73c8 Allocated by task 0: (stack is not available) The buggy address belongs to the object at ffff88810e943c00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 185 bytes inside of 512-byte region [ffff88810e943c00, ffff88810e943e00) The buggy address belongs to the page: page:ffffea00043a5000 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88810e943c00 pfn:0x10e940 head:ffffea00043a5000 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 ffffea000446e508 ffffea0004340a08 ffff888100043080 raw: ffff88810e943c00 0000000000100002 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 53, ts 32105132411, free_ts 32077743731 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x179/0x180 mm/page_alloc.c:2462 get_page_from_freelist+0x2235/0x23d0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5370 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1813 [inline] new_slab+0x84/0x3f0 mm/slub.c:1874 new_slab_objects mm/slub.c:2632 [inline] ___slab_alloc+0x2a6/0x450 mm/slub.c:2796 __slab_alloc+0x63/0xa0 mm/slub.c:2836 slab_alloc_node mm/slub.c:2918 [inline] slab_alloc mm/slub.c:2960 [inline] __kmalloc_track_caller+0x1ef/0x320 mm/slub.c:4541 __kmalloc_reserve net/core/skbuff.c:144 [inline] __alloc_skb+0xdc/0x520 net/core/skbuff.c:212 alloc_skb include/linux/skbuff.h:1126 [inline] nlmsg_new include/net/netlink.h:953 [inline] inet6_ifa_notify net/ipv6/addrconf.c:5526 [inline] __ipv6_ifa_notify+0x1e8/0xdb0 net/ipv6/addrconf.c:6149 ipv6_ifa_notify net/ipv6/addrconf.c:6202 [inline] addrconf_dad_completed+0x183/0xe80 net/ipv6/addrconf.c:4248 addrconf_dad_work+0xc18/0x1410 net/ipv6/addrconf.c:-1 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 page last free stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1349 [inline] __free_pages_ok+0x7fc/0x820 mm/page_alloc.c:1629 free_the_page mm/page_alloc.c:5431 [inline] __free_pages+0xdd/0x380 mm/page_alloc.c:5440 __free_slab+0xcf/0x190 mm/slub.c:1899 free_slab mm/slub.c:1914 [inline] discard_slab mm/slub.c:1920 [inline] unfreeze_partials+0x15f/0x190 mm/slub.c:2415 put_cpu_partial+0xc1/0x180 mm/slub.c:2451 __slab_free+0x2c9/0x3a0 mm/slub.c:3100 do_slab_free mm/slub.c:3196 [inline] ___cache_free+0x111/0x130 mm/slub.c:3215 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:440 kasan_slab_alloc include/linux/kasan.h:244 [inline] slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580 slab_alloc_node mm/slub.c:2952 [inline] slab_alloc mm/slub.c:2960 [inline] kmem_cache_alloc+0x165/0x2e0 mm/slub.c:2965 getname_flags+0xb9/0x500 fs/namei.c:141 getname fs/namei.c:212 [inline] user_path_create fs/namei.c:3665 [inline] do_mkdirat+0x4b/0x340 fs/namei.c:3805 __do_sys_mkdirat fs/namei.c:3823 [inline] __se_sys_mkdirat fs/namei.c:3821 [inline] __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3821 Memory state around the buggy address: ffff88810e943b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88810e943c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88810e943c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88810e943d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88810e943d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================