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BUG: KASAN: use-after-free in string_nocheck lib/vsprintf.c:641 [inline]
BUG: KASAN: use-after-free in string+0x20f/0x2a0 lib/vsprintf.c:723
Read of size 1 at addr ffff8881049b8410 by task syz.0.1398/6136

CPU: 0 PID: 6136 Comm: syz.0.1398 Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 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+0x100/0x140 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+0x20f/0x2a0 lib/vsprintf.c:723
 vsnprintf+0xec5/0x1990 lib/vsprintf.c:2689
 seq_vprintf fs/seq_file.c:398 [inline]
 seq_printf+0x185/0x280 fs/seq_file.c:413
 show_interrupts+0x921/0xa90 kernel/irq/proc.c:526
 seq_read_iter+0x908/0xce0 fs/seq_file.c:272
 proc_reg_read_iter+0x1be/0x290 fs/proc/inode.c:310
 call_read_iter include/linux/fs.h:2066 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x62a/0xa50 fs/read_write.c:496
 ksys_read+0x14a/0x260 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: 0033:0x7ffba1eba159
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:00007ffba0913028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007ffba2141fa0 RCX: 00007ffba1eba159
RDX: 00000000000003ee RSI: 0000200000000340 RDI: 0000000000000004
RBP: 00007ffba1f5106b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffba2142038 R14: 00007ffba2141fa0 R15: 00007ffc31d2a1a8

Allocated by task 4500:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:430 [inline]
 ____kasan_kmalloc mm/kasan/common.c:509 [inline]
 __kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:518
 kasan_kmalloc include/linux/kasan.h:254 [inline]
 __kmalloc+0x19f/0x330 mm/slub.c:4038
 __kmalloc_node include/linux/slab.h:421 [inline]
 kmalloc_node include/linux/slab.h:578 [inline]
 __vmalloc_area_node mm/vmalloc.c:2520 [inline]
 __vmalloc_node_range+0x294/0x7a0 mm/vmalloc.c:2629
 __vmalloc_node mm/vmalloc.c:2689 [inline]
 vzalloc+0x78/0x90 mm/vmalloc.c:2742
 alloc_counters+0x65/0x530 net/ipv4/netfilter/ip_tables.c:800
 copy_entries_to_user net/ipv4/netfilter/ip_tables.c:822 [inline]
 get_entries net/ipv4/netfilter/ip_tables.c:1021 [inline]
 do_ipt_get_ctl+0xa26/0x1100 net/ipv4/netfilter/ip_tables.c:1666
 nf_getsockopt+0x26d/0x290 net/netfilter/nf_sockopt.c:116
 ip_getsockopt+0x134c/0x17a0 net/ipv4/ip_sockglue.c:1797
 tcp_getsockopt+0x1e2/0x1ff0 net/ipv4/tcp.c:4049
 sock_common_getsockopt+0x98/0xb0 net/core/sock.c:3298
 __sys_getsockopt+0x201/0x370 net/socket.c:2188
 __do_sys_getsockopt net/socket.c:2203 [inline]
 __se_sys_getsockopt net/socket.c:2200 [inline]
 __x64_sys_getsockopt+0xbf/0xd0 net/socket.c:2200
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 4500:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1600 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
 slab_free mm/slub.c:3208 [inline]
 kfree+0xc0/0x270 mm/slub.c:4196
 kvfree+0x35/0x40 mm/util.c:647
 __vunmap+0x8e1/0x980 mm/vmalloc.c:2312
 __vfree mm/vmalloc.c:2356 [inline]
 vfree+0x61/0x90 mm/vmalloc.c:2387
 copy_entries_to_user net/ipv4/netfilter/ip_tables.c:865 [inline]
 get_entries net/ipv4/netfilter/ip_tables.c:1021 [inline]
 do_ipt_get_ctl+0xe21/0x1100 net/ipv4/netfilter/ip_tables.c:1666
 nf_getsockopt+0x26d/0x290 net/netfilter/nf_sockopt.c:116
 ip_getsockopt+0x134c/0x17a0 net/ipv4/ip_sockglue.c:1797
 tcp_getsockopt+0x1e2/0x1ff0 net/ipv4/tcp.c:4049
 sock_common_getsockopt+0x98/0xb0 net/core/sock.c:3298
 __sys_getsockopt+0x201/0x370 net/socket.c:2188
 __do_sys_getsockopt net/socket.c:2203 [inline]
 __se_sys_getsockopt net/socket.c:2200 [inline]
 __x64_sys_getsockopt+0xbf/0xd0 net/socket.c:2200
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff8881049b8410
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes inside of
 8-byte region [ffff8881049b8410, ffff8881049b8418)
The buggy address belongs to the page:
page:ffffea0004126e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1049b8
flags: 0x4000000000000200(slab)
raw: 4000000000000200 ffffea00045d5d80 0000000600000006 ffff888100043c80
raw: 0000000000000000 0000000000660066 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 16, ts 1608717057, free_ts 0
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x176/0x190 mm/page_alloc.c:2462
 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384
 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+0x2f8/0x4c0 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+0x1e4/0x310 mm/slub.c:4541
 kstrdup mm/util.c:63 [inline]
 kstrdup_const+0x55/0x90 mm/util.c:86
 __kernfs_new_node+0xa6/0x670 fs/kernfs/dir.c:658
 kernfs_new_node+0x150/0x260 fs/kernfs/dir.c:739
 kernfs_create_link+0xa4/0x200 fs/kernfs/symlink.c:39
 sysfs_do_create_link_sd+0x8a/0x110 fs/sysfs/symlink.c:44
 sysfs_do_create_link fs/sysfs/symlink.c:80 [inline]
 sysfs_create_link+0x68/0x80 fs/sysfs/symlink.c:92
 device_add_class_symlinks+0x210/0x2a0 drivers/base/core.c:3013
 device_add+0x4d2/0xc00 drivers/base/core.c:3221
 device_create_groups_vargs drivers/base/core.c:3960 [inline]
 device_create+0x26c/0x300 drivers/base/core.c:4002
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881049b8300: fc fc fc fc fa fc fc fc fc fa fc fc fc fc 00 fc
 ffff8881049b8380: fc fc fc 00 fc fc fc fc fa fc fc fc fc fa fc fc
>ffff8881049b8400: fc fc fa fc fc fc fc fa fc fc fc fc fa fc fc fc
                         ^
 ffff8881049b8480: fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc
 ffff8881049b8500: 00 fc fc fc fc fa fc fc fc fc fa fc fc fc fc fa
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