netlink: 8 bytes leftover after parsing attributes in process `syz-executor.4'. ================================================================== BUG: KASAN: use-after-free in atomic_sub_return include/asm-generic/atomic-instrumented.h:159 [inline] BUG: KASAN: use-after-free in skb_release_data+0x11d/0x7a0 net/core/skbuff.c:566 Write of size 4 at addr ffff88808a58e760 by task syz-executor.4/12690 CPU: 1 PID: 12690 Comm: syz-executor.4 Not tainted 5.0.0+ #109 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+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x123/0x190 mm/kasan/generic.c:191 kasan_check_write+0x14/0x20 mm/kasan/common.c:108 atomic_sub_return include/asm-generic/atomic-instrumented.h:159 [inline] skb_release_data+0x11d/0x7a0 net/core/skbuff.c:566 skb_release_all+0x4d/0x60 net/core/skbuff.c:631 __kfree_skb net/core/skbuff.c:645 [inline] kfree_skb net/core/skbuff.c:663 [inline] kfree_skb+0xe8/0x390 net/core/skbuff.c:657 skb_queue_purge+0x19/0x40 net/core/skbuff.c:2906 packet_release+0x8eb/0xbf0 net/packet/af_packet.c:3026 __sock_release+0xd3/0x2b0 net/socket.c:599 sock_close+0x1b/0x30 net/socket.c:1247 __fput+0x2e5/0x8d0 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x14a/0x1c0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x90a/0x2fa0 kernel/exit.c:876 do_group_exit+0x135/0x370 kernel/exit.c:980 get_signal+0x399/0x1d50 kernel/signal.c:2575 do_signal+0x87/0x1940 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458209 Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f9ed916ec78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: 000000000000004c RBX: 0000000000000003 RCX: 0000000000458209 RDX: 0000000000000000 RSI: 0000000020000100 RDI: 000000000000000b RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9ed916f6d4 R13: 00000000004c5187 R14: 00000000004d8f38 R15: 00000000ffffffff Allocated by task 12696: save_stack+0x45/0xd0 mm/kasan/common.c:75 set_track mm/kasan/common.c:87 [inline] __kasan_kmalloc mm/kasan/common.c:497 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:470 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:511 __do_kmalloc_node mm/slab.c:3686 [inline] __kmalloc_node_track_caller+0x4e/0x70 mm/slab.c:3700 __kmalloc_reserve.isra.0+0x40/0xf0 net/core/skbuff.c:140 __alloc_skb+0x10b/0x5e0 net/core/skbuff.c:208 alloc_skb_fclone include/linux/skbuff.h:1107 [inline] sk_stream_alloc_skb+0x113/0xd10 net/ipv4/tcp.c:889 tcp_connect+0xfd8/0x4280 net/ipv4/tcp_output.c:3521 tcp_v6_connect+0x150b/0x20a0 net/ipv6/tcp_ipv6.c:330 __inet_stream_connect+0x83f/0xea0 net/ipv4/af_inet.c:659 tcp_sendmsg_fastopen net/ipv4/tcp.c:1158 [inline] tcp_sendmsg_locked+0x2314/0x34d0 net/ipv4/tcp.c:1200 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1434 inet_sendmsg+0x147/0x5e0 net/ipv4/af_inet.c:802 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xdd/0x130 net/socket.c:661 __sys_sendto+0x262/0x380 net/socket.c:1932 __do_sys_sendto net/socket.c:1944 [inline] __se_sys_sendto net/socket.c:1940 [inline] __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1940 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 12690: save_stack+0x45/0xd0 mm/kasan/common.c:75 set_track mm/kasan/common.c:87 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:459 kasan_slab_free+0xe/0x10 mm/kasan/common.c:467 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3821 skb_free_head+0x93/0xb0 net/core/skbuff.c:557 skb_release_data+0x576/0x7a0 net/core/skbuff.c:577 skb_release_all+0x4d/0x60 net/core/skbuff.c:631 __kfree_skb net/core/skbuff.c:645 [inline] kfree_skb net/core/skbuff.c:663 [inline] kfree_skb+0xe8/0x390 net/core/skbuff.c:657 skb_queue_purge+0x19/0x40 net/core/skbuff.c:2906 packet_release+0x8eb/0xbf0 net/packet/af_packet.c:3026 __sock_release+0xd3/0x2b0 net/socket.c:599 sock_close+0x1b/0x30 net/socket.c:1247 __fput+0x2e5/0x8d0 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x14a/0x1c0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x90a/0x2fa0 kernel/exit.c:876 do_group_exit+0x135/0x370 kernel/exit.c:980 get_signal+0x399/0x1d50 kernel/signal.c:2575 do_signal+0x87/0x1940 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff88808a58e480 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 736 bytes inside of 1024-byte region [ffff88808a58e480, ffff88808a58e880) The buggy address belongs to the page: page:ffffea0002296380 count:1 mapcount:0 mapping:ffff88812c3f0ac0 index:0xffff88808a58e000 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea0002457d88 ffffea00015f3408 ffff88812c3f0ac0 raw: ffff88808a58e000 ffff88808a58e000 0000000100000005 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808a58e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808a58e680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88808a58e700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88808a58e780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808a58e800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================