================================================================== BUG: KASAN: use-after-free in strlen+0x53/0x60 lib/string.c:581 Read of size 1 at addr ffff88801ec9f7e0 by task cifsd/6270 CPU: 0 PID: 6270 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 strlen+0x53/0x60 lib/string.c:581 reconn_set_ipaddr_from_hostname+0xc5/0x580 fs/cifs/connect.c:100 __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 6263: 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:1541 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 6263: 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:1541 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 ffff88801ec9f7e0 which belongs to the cache kmalloc-16 of size 16 The buggy address is located 0 bytes inside of 16-byte region [ffff88801ec9f7e0, ffff88801ec9f7f0) The buggy address belongs to the page: page:ffffea00007b27c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1ec9f flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 ffffea00005ee180 0000000a0000000a 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 0x12c00(GFP_NOIO|__GFP_NOWARN|__GFP_NORETRY), pid 1, ts 6139897445, free_ts 6133993783 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_pages_node include/linux/gfp.h:570 [inline] alloc_slab_page mm/slub.c:1782 [inline] allocate_slab mm/slub.c:1917 [inline] new_slab+0xb6/0x4b0 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_array_node include/linux/slab.h:700 [inline] blk_mq_alloc_hctx block/blk-mq.c:2830 [inline] blk_mq_alloc_and_init_hctx block/blk-mq.c:3220 [inline] blk_mq_realloc_hw_ctxs+0x740/0x1730 block/blk-mq.c:3272 blk_mq_init_allocated_queue+0x3db/0x17b0 block/blk-mq.c:3333 blk_mq_init_queue_data block/blk-mq.c:3168 [inline] __blk_mq_alloc_disk+0x81/0x150 block/blk-mq.c:3188 nbd_dev_add+0x397/0xb20 drivers/block/nbd.c:1743 nbd_init+0x21c/0x2c0 drivers/block/nbd.c:2500 do_one_initcall+0x272/0x730 init/main.c:1276 do_initcall_level+0x13d/0x1f0 init/main.c:1349 do_initcalls+0x4b/0x90 init/main.c:1365 kernel_init_freeable+0x3d5/0x560 init/main.c:1589 kernel_init+0x19/0x1b0 init/main.c:1480 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 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 mm_free_pgd kernel/fork.c:654 [inline] __mmdrop+0xaa/0x3e0 kernel/fork.c:705 free_bprm+0x122/0x2d0 fs/exec.c:1494 kernel_execve+0x386/0x8e0 fs/exec.c:2015 call_usermodehelper_exec_async+0x207/0x350 kernel/umh.c:112 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Memory state around the buggy address: ffff88801ec9f680: 00 04 fc fc 00 00 fc fc 00 00 fc fc fa fb fc fc ffff88801ec9f700: 00 05 fc fc 00 05 fc fc fa fb fc fc fa fb fc fc >ffff88801ec9f780: fa fb fc fc 00 03 fc fc fa fb fc fc fa fb fc fc ^ ffff88801ec9f800: 00 06 fc fc fa fb fc fc 00 03 fc fc 00 00 fc fc ffff88801ec9f880: 00 00 fc fc 00 07 fc fc 00 07 fc fc 00 07 fc fc ==================================================================