================================================================== BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] BUG: KASAN: use-after-free in refcount_dec_not_one+0x71/0x1d0 lib/refcount.c:269 Read of size 4 at addr ffff8880958aeb98 by task syz-executor.2/15539 CPU: 1 PID: 15539 Comm: syz-executor.2 Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256 kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354 kasan_report+0x8f/0xa0 mm/kasan/report.c:412 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] refcount_dec_not_one+0x71/0x1d0 lib/refcount.c:269 refcount_dec_and_mutex_lock+0x1c/0x80 lib/refcount.c:308 nbd_put drivers/block/nbd.c:228 [inline] nbd_genl_connect+0x11ee/0x1630 drivers/block/nbd.c:1913 genl_family_rcv_msg+0x642/0xc40 net/netlink/genetlink.c:602 genl_rcv_msg+0xbf/0x160 net/netlink/genetlink.c:627 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463 genl_rcv+0x24/0x40 net/netlink/genetlink.c:638 netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline] netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351 netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xc3/0x120 net/socket.c:661 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227 __sys_sendmsg net/socket.c:2265 [inline] __do_sys_sendmsg net/socket.c:2274 [inline] __se_sys_sendmsg net/socket.c:2272 [inline] __x64_sys_sendmsg+0x132/0x220 net/socket.c:2272 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f1cb159b0f9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f1cafacb168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f1cb16bb120 RCX: 00007f1cb159b0f9 RDX: 3cf9020000000000 RSI: 0000000020000380 RDI: 0000000000000016 RBP: 00007f1cb15f6ae9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc62ad22ff R14: 00007f1cafacb300 R15: 0000000000022000 Allocated by task 15539: kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625 kmalloc include/linux/slab.h:515 [inline] kzalloc include/linux/slab.h:709 [inline] nbd_dev_add+0x44/0x890 drivers/block/nbd.c:1627 nbd_genl_connect+0x488/0x1630 drivers/block/nbd.c:1784 genl_family_rcv_msg+0x642/0xc40 net/netlink/genetlink.c:602 genl_rcv_msg+0xbf/0x160 net/netlink/genetlink.c:627 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463 genl_rcv+0x24/0x40 net/netlink/genetlink.c:638 netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline] netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351 netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xc3/0x120 net/socket.c:661 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227 __sys_sendmsg net/socket.c:2265 [inline] __do_sys_sendmsg net/socket.c:2274 [inline] __se_sys_sendmsg net/socket.c:2272 [inline] __x64_sys_sendmsg+0x132/0x220 net/socket.c:2272 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 15539: __cache_free mm/slab.c:3503 [inline] kfree+0xcc/0x210 mm/slab.c:3822 nbd_dev_remove drivers/block/nbd.c:223 [inline] nbd_put.part.0+0xfe/0x140 drivers/block/nbd.c:231 nbd_put drivers/block/nbd.c:275 [inline] nbd_config_put+0x6a0/0x870 drivers/block/nbd.c:1185 nbd_genl_connect+0x11bb/0x1630 drivers/block/nbd.c:1911 genl_family_rcv_msg+0x642/0xc40 net/netlink/genetlink.c:602 genl_rcv_msg+0xbf/0x160 net/netlink/genetlink.c:627 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463 genl_rcv+0x24/0x40 net/netlink/genetlink.c:638 netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline] netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351 netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xc3/0x120 net/socket.c:661 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227 __sys_sendmsg net/socket.c:2265 [inline] __do_sys_sendmsg net/socket.c:2274 [inline] __se_sys_sendmsg net/socket.c:2272 [inline] __x64_sys_sendmsg+0x132/0x220 net/socket.c:2272 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880958aeac0 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 216 bytes inside of 512-byte region [ffff8880958aeac0, ffff8880958aecc0) The buggy address belongs to the page: page:ffffea0002562b80 count:1 mapcount:0 mapping:ffff88813bff0940 index:0xffff8880958ae5c0 flags: 0xfff00000000100(slab) raw: 00fff00000000100 ffffea0002ac8808 ffffea0002c35648 ffff88813bff0940 raw: ffff8880958ae5c0 ffff8880958ae0c0 0000000100000004 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880958aea80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff8880958aeb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880958aeb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880958aec00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880958aec80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ==================================================================