================================================================== BUG: KASAN: use-after-free in atomic_sub_return include/asm-generic/atomic-instrumented.h:305 [inline] BUG: KASAN: use-after-free in skb_release_data+0x1a3/0x9a0 net/core/skbuff.c:559 Write of size 4 at addr ffff8881c4afa920 by task syz-executor3/32653 CPU: 1 PID: 32653 Comm: syz-executor3 Not tainted 4.20.0-rc4+ #219 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+0x244/0x39d lib/dump_stack.c:113 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278 atomic_sub_return include/asm-generic/atomic-instrumented.h:305 [inline] skb_release_data+0x1a3/0x9a0 net/core/skbuff.c:559 skb_release_all+0x4a/0x60 net/core/skbuff.c:627 __kfree_skb net/core/skbuff.c:641 [inline] kfree_skb+0x1bb/0x580 net/core/skbuff.c:659 sit_tunnel_xmit+0x173/0x30d0 net/ipv6/sit.c:1044 __netdev_start_xmit include/linux/netdevice.h:4356 [inline] netdev_start_xmit include/linux/netdevice.h:4365 [inline] xmit_one net/core/dev.c:3257 [inline] dev_hard_start_xmit+0x295/0xc80 net/core/dev.c:3273 __dev_queue_xmit+0x2f71/0x3ad0 net/core/dev.c:3843 dev_queue_xmit+0x17/0x20 net/core/dev.c:3876 packet_sendmsg_spkt+0xf44/0x16e9 net/packet/af_packet.c:1975 sock_sendmsg_nosec net/socket.c:621 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:631 ___sys_sendmsg+0x51d/0x930 net/socket.c:2116 __sys_sendmmsg+0x246/0x6d0 net/socket.c:2211 __do_sys_sendmmsg net/socket.c:2240 [inline] __se_sys_sendmmsg net/socket.c:2237 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2237 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457569 Code: fd b3 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 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f37ee477c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000457569 RDX: 0000000000000573 RSI: 0000000020003980 RDI: 0000000000000003 RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f37ee4786d4 R13: 00000000004c3c33 R14: 00000000004d6248 R15: 00000000ffffffff Allocated by task 32653: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 __do_kmalloc_node mm/slab.c:3684 [inline] __kmalloc_node_track_caller+0x50/0x70 mm/slab.c:3698 __kmalloc_reserve.isra.40+0x41/0xe0 net/core/skbuff.c:137 __alloc_skb+0x155/0x770 net/core/skbuff.c:205 alloc_skb include/linux/skbuff.h:997 [inline] sock_wmalloc+0x16d/0x1f0 net/core/sock.c:1935 packet_sendmsg_spkt+0x48a/0x16e9 net/packet/af_packet.c:1922 sock_sendmsg_nosec net/socket.c:621 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:631 ___sys_sendmsg+0x51d/0x930 net/socket.c:2116 __sys_sendmmsg+0x246/0x6d0 net/socket.c:2211 __do_sys_sendmmsg net/socket.c:2240 [inline] __se_sys_sendmmsg net/socket.c:2237 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2237 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 32653: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3817 skb_free_head+0x99/0xc0 net/core/skbuff.c:550 skb_release_data+0x70c/0x9a0 net/core/skbuff.c:570 skb_release_all+0x4a/0x60 net/core/skbuff.c:627 __kfree_skb net/core/skbuff.c:641 [inline] consume_skb+0x1ae/0x570 net/core/skbuff.c:701 packet_rcv+0x172/0x1840 net/packet/af_packet.c:2139 dev_queue_xmit_nit+0x927/0xc90 net/core/dev.c:2053 xmit_one net/core/dev.c:3253 [inline] dev_hard_start_xmit+0x186/0xc80 net/core/dev.c:3273 __dev_queue_xmit+0x2f71/0x3ad0 net/core/dev.c:3843 dev_queue_xmit+0x17/0x20 net/core/dev.c:3876 packet_sendmsg_spkt+0xf44/0x16e9 net/packet/af_packet.c:1975 sock_sendmsg_nosec net/socket.c:621 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:631 ___sys_sendmsg+0x51d/0x930 net/socket.c:2116 __sys_sendmmsg+0x246/0x6d0 net/socket.c:2211 __do_sys_sendmmsg net/socket.c:2240 [inline] __se_sys_sendmmsg net/socket.c:2237 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2237 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8881c4afa840 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 224 bytes inside of 512-byte region [ffff8881c4afa840, ffff8881c4afaa40) The buggy address belongs to the page: page:ffffea000712be80 count:1 mapcount:0 mapping:ffff8881da800940 index:0x0 flags: 0x2fffc0000000200(slab) raw: 02fffc0000000200 ffffea00065bc948 ffffea0006140488 ffff8881da800940 raw: 0000000000000000 ffff8881c4afa0c0 0000000100000006 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881c4afa800: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff8881c4afa880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881c4afa900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881c4afa980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881c4afaa00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ==================================================================