================================================================== BUG: KASAN: use-after-free in string_nocheck lib/vsprintf.c:642 [inline] BUG: KASAN: use-after-free in string+0x204/0x290 lib/vsprintf.c:724 Read of size 1 at addr ffff8880572c37e0 by task cifsd/4528 CPU: 1 PID: 4528 Comm: cifsd 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 vscnprintf lib/vsprintf.c:2914 [inline] scnprintf+0xe5/0x180 lib/vsprintf.c:2968 reconn_set_ipaddr_from_hostname+0x112/0x580 fs/cifs/connect.c:107 __cifs_reconnect fs/cifs/connect.c:288 [inline] cifs_reconnect+0x470/0x1350 fs/cifs/connect.c:447 cifs_readv_from_socket+0x7c4/0x8b0 fs/cifs/connect.c:-1 cifs_read_from_socket fs/cifs/connect.c:626 [inline] cifs_demultiplex_thread+0x53b/0x35b0 fs/cifs/connect.c:989 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Allocated by task 4527: 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 kstrdup+0x32/0x70 mm/util.c:60 cifs_get_tcp_session+0xde/0x18f0 fs/cifs/connect.c:1431 mount_get_conns+0xc3/0xe00 fs/cifs/connect.c:2988 is_dfs_mount fs/cifs/connect.c:3354 [inline] cifs_mount+0x162/0x1380 fs/cifs/connect.c:3549 cifs_smb3_do_mount+0x366/0x760 fs/cifs/cifsfs.c:895 smb3_get_tree_common fs/cifs/fs_context.c:708 [inline] smb3_get_tree+0x59a/0xa80 fs/cifs/fs_context.c:726 vfs_get_tree+0x88/0x270 fs/super.c:1530 do_new_mount+0x247/0xa40 fs/namespace.c:3034 do_mount fs/namespace.c:3377 [inline] __do_sys_mount fs/namespace.c:3585 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562 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 Freed by task 4527: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:46 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1710 [inline] slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736 slab_free mm/slub.c:3504 [inline] kfree+0xef/0x2a0 mm/slub.c:4564 cifs_put_tcp_session+0x2e1/0x3d0 fs/cifs/connect.c:1404 mount_put_conns+0xb0/0x270 fs/cifs/connect.c:2969 cifs_mount+0xbf5/0x1380 fs/cifs/connect.c:3597 cifs_smb3_do_mount+0x366/0x760 fs/cifs/cifsfs.c:895 smb3_get_tree_common fs/cifs/fs_context.c:708 [inline] smb3_get_tree+0x59a/0xa80 fs/cifs/fs_context.c:726 vfs_get_tree+0x88/0x270 fs/super.c:1530 do_new_mount+0x247/0xa40 fs/namespace.c:3034 do_mount fs/namespace.c:3377 [inline] __do_sys_mount fs/namespace.c:3585 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562 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 ffff8880572c37e0 which belongs to the cache kmalloc-16 of size 16 The buggy address is located 0 bytes inside of 16-byte region [ffff8880572c37e0, ffff8880572c37f0) The buggy address belongs to the page: page:ffffea00015cb0c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x572c3 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 0000000000000000 dead000000000122 ffff888016c413c0 raw: 0000000000000000 0000000000800080 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 4322, ts 88066768690, free_ts 88066684876 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] __kmalloc_node+0x142/0x3a0 mm/slub.c:4456 kmalloc_node include/linux/slab.h:630 [inline] kvmalloc_node+0x84/0x130 mm/util.c:619 translate_table+0x191/0x2020 net/ipv6/netfilter/ip6_tables.c:697 do_replace net/ipv6/netfilter/ip6_tables.c:1154 [inline] do_ip6t_set_ctl+0x96c/0xd90 net/ipv6/netfilter/ip6_tables.c:1643 nf_setsockopt+0x25f/0x280 net/netfilter/nf_sockopt.c:101 ipv6_setsockopt+0x20ba/0x3cc0 net/ipv6/ipv6_sockglue.c:1014 tcp_setsockopt+0x229/0x1e60 net/ipv4/tcp.c:3722 __sys_setsockopt+0x2bf/0x3d0 net/socket.c:2213 __do_sys_setsockopt net/socket.c:2224 [inline] __se_sys_setsockopt net/socket.c:2221 [inline] __x64_sys_setsockopt+0xb1/0xc0 net/socket.c:2221 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 __vunmap+0x8e0/0xa80 mm/vmalloc.c:2628 copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:882 [inline] get_entries net/ipv6/netfilter/ip6_tables.c:1039 [inline] do_ip6t_get_ctl+0xe4b/0x1130 net/ipv6/netfilter/ip6_tables.c:1676 nf_getsockopt+0x25e/0x280 net/netfilter/nf_sockopt.c:116 ipv6_getsockopt+0x43f/0x2390 net/ipv6/ipv6_sockglue.c:1492 tcp_getsockopt+0x209/0x2530 net/ipv4/tcp.c:4323 __sys_getsockopt+0x1b0/0x230 net/socket.c:2257 __do_sys_getsockopt net/socket.c:2272 [inline] __se_sys_getsockopt net/socket.c:2269 [inline] __x64_sys_getsockopt+0xb1/0xc0 net/socket.c:2269 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 Memory state around the buggy address: ffff8880572c3680: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc ffff8880572c3700: fa fb fc fc fa fb fc fc 00 06 fc fc 00 00 fc fc >ffff8880572c3780: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc ^ ffff8880572c3800: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc ffff8880572c3880: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc ==================================================================