================================================================== BUG: KASAN: use-after-free in ex_handler_refcount+0x18f/0x1c0 arch/x86/mm/extable.c:49 Write of size 4 at addr ffff8880a94fc3d8 by task systemd-udevd/26091 CPU: 0 PID: 26091 Comm: systemd-udevd Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 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 mm/kasan/report.c:412 [inline] __asan_report_store4_noabort+0x88/0x90 mm/kasan/report.c:437 ex_handler_refcount+0x18f/0x1c0 arch/x86/mm/extable.c:49 fixup_exception+0x8a/0xd0 arch/x86/mm/extable.c:197 do_trap_no_signal arch/x86/kernel/traps.c:209 [inline] do_trap+0x61/0x250 arch/x86/kernel/traps.c:258 do_error_trap+0x15d/0x310 arch/x86/kernel/traps.c:303 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038 RIP: 0010:__noinstr_text_end+0x243b/0x7813 Code: 0f 0b 48 8d 4b 50 0f 0b 48 8d 4b 08 0f 0b 48 8d 4d 08 0f 0b 48 8d 8d 08 02 00 00 0f 0b 48 8d 0b 0f 0b 48 8d 0b 0f 0b 48 8d 0b <0f> 0b 48 8d 4d 00 0f 0b 49 8d 0c 24 0f 0b 48 8d 8b c0 00 00 00 0f RSP: 0018:ffff88804d6dfcd8 EFLAGS: 00010296 RAX: 0000000000000000 RBX: ffff8880a94fc3d8 RCX: ffff8880a94fc3d8 RDX: 0000000000000004 RSI: 0000000000000004 RDI: 0000000000000001 RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff14b7985 R10: ffffffff8a5bcc2b R11: 0000000000000000 R12: ffffffff8a5bcc20 R13: 0000000000000000 R14: 1ffff11011638f25 R15: dffffc0000000000 nbd_put drivers/block/nbd.c:228 [inline] nbd_release+0x108/0x170 drivers/block/nbd.c:1462 __blkdev_put+0x636/0x870 fs/block_dev.c:1819 blkdev_close+0x86/0xb0 fs/block_dev.c:1888 __fput+0x2ce/0x890 fs/file_table.c:278 task_work_run+0x148/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x251/0x2a0 arch/x86/entry/common.c:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f4f2e1ec270 Code: 73 01 c3 48 8b 0d 38 7d 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c1 20 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ee fb ff ff 48 89 04 24 RSP: 002b:00007fff6744d7c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007f4f2e1ec270 RDX: 000000000aba9500 RSI: 0000000000000000 RDI: 0000000000000007 RBP: 00007f4f2f0a6710 R08: 0000000000000045 R09: 0000000000000018 R10: 0000558eafa551b8 R11: 0000000000000246 R12: 0000000000000000 R13: 0000558eafa506e0 R14: 0000000000000003 R15: 000000000000000e Allocated by task 26003: 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+0x4cc/0x1630 drivers/block/nbd.c:1773 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 26003: __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:228 [inline] nbd_genl_connect+0x120e/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 The buggy address belongs to the object at ffff8880a94fc300 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 216 bytes inside of 512-byte region [ffff8880a94fc300, ffff8880a94fc500) The buggy address belongs to the page: page:ffffea0002a53f00 count:1 mapcount:0 mapping:ffff88813bff0940 index:0xffff8880a94fca80 flags: 0xfff00000000100(slab) raw: 00fff00000000100 ffffea00024de548 ffffea0002a7fa48 ffff88813bff0940 raw: ffff8880a94fca80 ffff8880a94fc080 0000000100000004 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a94fc280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a94fc300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880a94fc380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a94fc400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a94fc480: fb fb fb fb fb fb fb fb fb fb fb fb fb 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