================================================================== BUG: KASAN: use-after-free in string_nocheck lib/vsprintf.c:643 [inline] BUG: KASAN: use-after-free in string+0x204/0x290 lib/vsprintf.c:725 Read of size 1 at addr ffff88801d351bc0 by task cifsd/12246 CPU: 1 PID: 12246 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+0x188/0x24e lib/dump_stack.c:106 print_address_description mm/kasan/report.c:316 [inline] print_report+0xa8/0x210 mm/kasan/report.c:420 kasan_report+0x10b/0x140 mm/kasan/report.c:524 string_nocheck lib/vsprintf.c:643 [inline] string+0x204/0x290 lib/vsprintf.c:725 vsnprintf+0x10db/0x1c20 lib/vsprintf.c:2805 vscnprintf lib/vsprintf.c:2911 [inline] scnprintf+0xfb/0x180 lib/vsprintf.c:2964 reconn_set_ipaddr_from_hostname+0x152/0x600 fs/smb/client/connect.c:111 __cifs_reconnect+0x1a5/0x870 fs/smb/client/connect.c:444 cifs_reconnect+0x231/0xd20 fs/smb/client/connect.c:618 cifs_readv_from_socket+0x782/0x8d0 include/linux/spinlock.h:-1 cifs_read_from_socket fs/smb/client/connect.c:822 [inline] cifs_demultiplex_thread+0x523/0x35b0 fs/smb/client/connect.c:1232 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Allocated by task 12244: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 ____kasan_kmalloc mm/kasan/common.c:375 [inline] __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slab_common.c:936 [inline] __kmalloc_node_track_caller+0xb0/0x240 mm/slab_common.c:956 kstrdup+0x37/0x70 mm/util.c:61 cifs_get_tcp_session+0xea/0x1ad0 fs/smb/client/connect.c:1740 mount_get_conns+0xb6/0xec0 fs/smb/client/connect.c:3367 is_dfs_mount fs/smb/client/connect.c:3746 [inline] cifs_mount+0x16a/0x13c0 fs/smb/client/connect.c:3951 cifs_smb3_do_mount+0x366/0x760 fs/smb/client/cifsfs.c:948 smb3_get_tree_common fs/smb/client/fs_context.c:712 [inline] smb3_get_tree+0x5a1/0xa90 fs/smb/client/fs_context.c:732 vfs_get_tree+0x88/0x270 fs/super.c:1584 do_new_mount+0x247/0xa40 fs/namespace.c:3078 do_mount fs/namespace.c:3421 [inline] __do_sys_mount fs/namespace.c:3629 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3606 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Freed by task 12244: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1729 [inline] slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755 slab_free mm/slub.c:3687 [inline] __kmem_cache_free+0xb6/0x200 mm/slub.c:3700 cifs_put_tcp_session+0x319/0x400 fs/smb/client/connect.c:1712 mount_put_conns+0xb0/0x270 fs/smb/client/connect.c:3348 cifs_mount+0x1097/0x13c0 fs/smb/client/connect.c:4000 cifs_smb3_do_mount+0x366/0x760 fs/smb/client/cifsfs.c:948 smb3_get_tree_common fs/smb/client/fs_context.c:712 [inline] smb3_get_tree+0x5a1/0xa90 fs/smb/client/fs_context.c:732 vfs_get_tree+0x88/0x270 fs/super.c:1584 do_new_mount+0x247/0xa40 fs/namespace.c:3078 do_mount fs/namespace.c:3421 [inline] __do_sys_mount fs/namespace.c:3629 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3606 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 The buggy address belongs to the object at ffff88801d351bc0 which belongs to the cache kmalloc-16 of size 16 The buggy address is located 0 bytes inside of 16-byte region [ffff88801d351bc0, ffff88801d351bd0) The buggy address belongs to the physical page: page:ffffea000074d440 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88801d351fa0 pfn:0x1d351 flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 0000000000000000 dead000000000001 ffff8880174413c0 raw: ffff88801d351fa0 000000008080006b 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 4286, tgid 4286 (syz-executor), ts 89231740699, free_ts 86044182918 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2560 prep_new_page mm/page_alloc.c:2567 [inline] get_page_from_freelist+0x206b/0x2180 mm/page_alloc.c:4358 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5658 alloc_slab_page+0x5d/0x180 mm/slub.c:1799 allocate_slab mm/slub.c:1944 [inline] new_slab+0x87/0x2d0 mm/slub.c:1997 ___slab_alloc+0xbc5/0x1240 mm/slub.c:3154 __slab_alloc mm/slub.c:3240 [inline] slab_alloc_node mm/slub.c:3325 [inline] __kmem_cache_alloc_node+0x126/0x270 mm/slub.c:3398 __do_kmalloc_node mm/slab_common.c:935 [inline] __kmalloc+0xa3/0x240 mm/slab_common.c:949 kmalloc include/linux/slab.h:568 [inline] kzalloc include/linux/slab.h:699 [inline] xt_jumpstack_alloc net/netfilter/x_tables.c:1357 [inline] xt_replace_table+0x8c/0x790 net/netfilter/x_tables.c:1416 xt_register_table+0x151/0x450 net/netfilter/x_tables.c:1502 ipt_register_table+0x160/0x7b0 net/ipv4/netfilter/ip_tables.c:1747 iptable_security_table_init+0x3d/0x60 net/ipv4/netfilter/iptable_security.c:46 xt_find_table_lock+0x220/0x360 net/netfilter/x_tables.c:1282 xt_request_find_table_lock+0x22/0x100 net/netfilter/x_tables.c:1307 get_info net/ipv4/netfilter/ip_tables.c:963 [inline] do_ipt_get_ctl+0x6e2/0x11a0 net/ipv4/netfilter/ip_tables.c:1658 nf_getsockopt+0x25e/0x280 net/netfilter/nf_sockopt.c:116 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1487 [inline] free_pcp_prepare mm/page_alloc.c:1537 [inline] free_unref_page_prepare+0x8e5/0x9e0 mm/page_alloc.c:3414 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3509 qlink_free mm/kasan/quarantine.c:168 [inline] qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187 kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294 __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737 slab_alloc_node mm/slub.c:3359 [inline] kmem_cache_alloc_node+0x1ad/0x310 mm/slub.c:3404 __alloc_skb+0xf9/0x7d0 net/core/skbuff.c:505 alloc_skb include/linux/skbuff.h:1303 [inline] nlmsg_new include/net/netlink.h:998 [inline] netlink_ack+0x373/0x1160 net/netlink/af_netlink.c:2453 netlink_rcv_skb+0x26d/0x440 net/netlink/af_netlink.c:2522 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] __sys_sendto+0x497/0x650 net/socket.c:2153 __do_sys_sendto net/socket.c:2165 [inline] __se_sys_sendto net/socket.c:2161 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:2161 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Memory state around the buggy address: ffff88801d351a80: 00 05 fc fc 00 00 fc fc fa fb fc fc fa fb fc fc ffff88801d351b00: fb fb fc fc fa fb fc fc fa fb fc fc 00 00 fc fc >ffff88801d351b80: fa fb fc fc 00 01 fc fc fa fb fc fc 00 05 fc fc ^ ffff88801d351c00: 00 00 fc fc fb fb fc fc fb fb fc fc fb fb fc fc ffff88801d351c80: 00 04 fc fc 00 05 fc fc 00 06 fc fc 00 00 fc fc ==================================================================