netlink: 4 bytes leftover after parsing attributes in process `syz-executor290'. netlink: 4 bytes leftover after parsing attributes in process `syz-executor290'. netlink: 4 bytes leftover after parsing attributes in process `syz-executor290'. ================================================================== BUG: KASAN: use-after-free in ex_handler_refcount+0x141/0x180 arch/x86/mm/extable.c:49 Write of size 4 at addr ffff8880aa7fd658 by task systemd-udevd/8494 CPU: 0 PID: 8494 Comm: systemd-udevd Not tainted 4.14.275-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x14b/0x1e7 lib/dump_stack.c:58 print_address_description.cold.6+0x9/0x1ca mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold.7+0x11a/0x2d3 mm/kasan/report.c:393 __asan_report_store4_noabort+0x17/0x20 mm/kasan/report.c:434 ex_handler_refcount+0x141/0x180 arch/x86/mm/extable.c:49 fixup_exception+0x7c/0xc0 arch/x86/mm/extable.c:197 do_trap_no_signal arch/x86/kernel/traps.c:208 [inline] do_trap+0x62/0x240 arch/x86/kernel/traps.c:257 do_error_trap+0x159/0x310 arch/x86/kernel/traps.c:301 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:964 RIP: 0010:flags_string.cold.10+0x1a14/0x6895 RSP: 0018:ffff88809d8f7c30 EFLAGS: 00010296 RAX: 0000000000000000 RBX: ffff8880aa7fd658 RCX: ffff8880aa7fd658 RDX: ffffed1013b1ef5a RSI: 0000000000000003 RDI: ffffffff8afb6bc0 RBP: ffff88809d8f7c48 R08: 0000000000000001 R09: 0000000000000000 R10: ffff88809d8f7c20 R11: ffff88809d8f7b97 R12: 0000000000000000 R13: ffffffff895129c0 R14: ffff88808821a840 R15: ffff88808821a900 nbd_put+0x1f/0x150 drivers/block/nbd.c:228 nbd_release+0xe1/0x140 drivers/block/nbd.c:1446 __blkdev_put+0x621/0x7c0 fs/block_dev.c:1803 blkdev_put+0x73/0x470 fs/block_dev.c:1868 blkdev_close+0x88/0xd0 fs/block_dev.c:1875 __fput+0x232/0x740 fs/file_table.c:210 ____fput+0x9/0x10 fs/file_table.c:244 task_work_run+0xe5/0x170 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x14a/0x190 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x416/0x5b0 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7fcb2c9bf270 RSP: 002b:00007ffcaa7cb8e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007fcb2c9bf270 RDX: 000000000aba9500 RSI: 0000000000000000 RDI: 0000000000000007 RBP: 00007fcb2d879710 R08: 0000000000000045 R09: 0000000000000018 R10: 000055c84cef4e38 R11: 0000000000000246 R12: 0000000000000000 R13: 000055c84cf03700 R14: 0000000000000003 R15: 000000000000000e Allocated by task 8470: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:551 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:536 kmem_cache_alloc_trace+0x152/0x3f0 mm/slab.c:3618 kmalloc include/linux/slab.h:488 [inline] kzalloc include/linux/slab.h:661 [inline] nbd_dev_add+0x8a/0x7c0 drivers/block/nbd.c:1611 nbd_genl_connect+0x394/0x1540 drivers/block/nbd.c:1756 genl_family_rcv_msg+0x57f/0xfe0 net/netlink/genetlink.c:600 genl_rcv_msg+0xa7/0x140 net/netlink/genetlink.c:625 netlink_rcv_skb+0x12f/0x3b0 net/netlink/af_netlink.c:2446 genl_rcv+0x23/0x40 net/netlink/genetlink.c:636 netlink_unicast_kernel net/netlink/af_netlink.c:1294 [inline] netlink_unicast+0x40b/0x610 net/netlink/af_netlink.c:1320 netlink_sendmsg+0x651/0xc10 net/netlink/af_netlink.c:1891 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:656 ___sys_sendmsg+0x625/0x920 net/socket.c:2062 __sys_sendmsg+0xc1/0x140 net/socket.c:2096 SYSC_sendmsg net/socket.c:2107 [inline] SyS_sendmsg+0xd/0x20 net/socket.c:2103 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb Freed by task 8483: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0xab/0x190 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcc/0x270 mm/slab.c:3815 nbd_dev_remove drivers/block/nbd.c:223 [inline] nbd_put drivers/block/nbd.c:231 [inline] nbd_put+0x113/0x150 drivers/block/nbd.c:226 nbd_genl_connect+0xcde/0x1540 drivers/block/nbd.c:1896 genl_family_rcv_msg+0x57f/0xfe0 net/netlink/genetlink.c:600 genl_rcv_msg+0xa7/0x140 net/netlink/genetlink.c:625 netlink_rcv_skb+0x12f/0x3b0 net/netlink/af_netlink.c:2446 genl_rcv+0x23/0x40 net/netlink/genetlink.c:636 netlink_unicast_kernel net/netlink/af_netlink.c:1294 [inline] netlink_unicast+0x40b/0x610 net/netlink/af_netlink.c:1320 netlink_sendmsg+0x651/0xc10 net/netlink/af_netlink.c:1891 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:656 ___sys_sendmsg+0x625/0x920 net/socket.c:2062 __sys_sendmsg+0xc1/0x140 net/socket.c:2096 SYSC_sendmsg net/socket.c:2107 [inline] SyS_sendmsg+0xd/0x20 net/socket.c:2103 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb The buggy address belongs to the object at ffff8880aa7fd580 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 216 bytes inside of 512-byte region [ffff8880aa7fd580, ffff8880aa7fd780) The buggy address belongs to the page: page:ffffea0002a9ff40 count:1 mapcount:0 mapping:ffff8880aa7fd080 index:0x0 flags: 0xfff00000000100(slab) raw: 00fff00000000100 ffff8880aa7fd080 0000000000000000 0000000100000006 raw: ffffea0002ac8160 ffffea0002aa9d60 ffff88813fe50940 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880aa7fd500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880aa7fd580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880aa7fd600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880aa7fd680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880aa7fd700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================