================================================================== BUG: KASAN: use-after-free in instrument_atomic_write include/linux/instrumented.h:71 [inline] BUG: KASAN: use-after-free in atomic_sub_return include/asm-generic/atomic-instrumented.h:160 [inline] BUG: KASAN: use-after-free in skb_release_data+0x11a/0x910 net/core/skbuff.c:599 Write of size 4 at addr ffff888091125ce0 by task syz-executor.2/14179 CPU: 1 PID: 14179 Comm: syz-executor.2 Not tainted 5.8.0-rc1-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+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 check_memory_region_inline mm/kasan/generic.c:186 [inline] check_memory_region+0x13d/0x180 mm/kasan/generic.c:192 instrument_atomic_write include/linux/instrumented.h:71 [inline] atomic_sub_return include/asm-generic/atomic-instrumented.h:160 [inline] skb_release_data+0x11a/0x910 net/core/skbuff.c:599 skb_release_all net/core/skbuff.c:664 [inline] __kfree_skb net/core/skbuff.c:678 [inline] kfree_skb.part.0+0xc2/0x350 net/core/skbuff.c:696 kfree_skb+0x7d/0x100 include/linux/refcount.h:270 ip6_tnl_start_xmit+0x717/0x16f0 net/ipv6/ip6_tunnel.c:1460 __netdev_start_xmit include/linux/netdevice.h:4611 [inline] netdev_start_xmit include/linux/netdevice.h:4625 [inline] xmit_one net/core/dev.c:3556 [inline] dev_hard_start_xmit+0x193/0x950 net/core/dev.c:3572 __dev_queue_xmit+0x2091/0x2d60 net/core/dev.c:4131 packet_sendmsg_spkt+0xd9a/0x13b0 net/packet/af_packet.c:1992 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45ca59 Code: Bad RIP value. RSP: 002b:00007f7029490c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000501e40 RCX: 000000000045ca59 RDX: 0000000000008000 RSI: 0000000020001140 RDI: 0000000000000003 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000a2b R14: 00000000004cd0f1 R15: 00007f70294916d4 Allocated by task 14179: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494 __kmalloc_reserve net/core/skbuff.c:142 [inline] __alloc_skb+0xae/0x550 net/core/skbuff.c:210 alloc_skb include/linux/skbuff.h:1083 [inline] sock_wmalloc+0xd0/0x120 net/core/sock.c:2205 packet_sendmsg_spkt+0x483/0x13b0 net/packet/af_packet.c:1939 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 14179: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] kasan_set_free_info mm/kasan/common.c:316 [inline] __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455 __cache_free mm/slab.c:3426 [inline] kfree+0x103/0x2c0 mm/slab.c:3757 skb_free_head net/core/skbuff.c:590 [inline] skb_release_data+0x6d9/0x910 net/core/skbuff.c:610 skb_release_all net/core/skbuff.c:664 [inline] __kfree_skb net/core/skbuff.c:678 [inline] consume_skb net/core/skbuff.c:837 [inline] consume_skb+0xc2/0x160 net/core/skbuff.c:831 packet_rcv+0xea/0x13b0 net/packet/af_packet.c:2154 dev_queue_xmit_nit+0x7f6/0xac0 net/core/dev.c:2355 xmit_one net/core/dev.c:3552 [inline] dev_hard_start_xmit+0xaa/0x950 net/core/dev.c:3572 __dev_queue_xmit+0x2091/0x2d60 net/core/dev.c:4131 packet_sendmsg_spkt+0xd9a/0x13b0 net/packet/af_packet.c:1992 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff888091125c00 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 224 bytes inside of 512-byte region [ffff888091125c00, ffff888091125e00) The buggy address belongs to the page: page:ffffea0002444940 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea000250b788 ffffea00028ae7c8 ffff8880aa000a80 raw: 0000000000000000 ffff888091125000 0000000100000004 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888091125b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888091125c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888091125c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888091125d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888091125d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================