bisecting fixing commit since 43598c571e7ed29e4c81e35b4a870fe6b9f8d58e
building syzkaller on 598ca6c8b8766304c3b2865e38f5f301c39bd299
testing commit 43598c571e7ed29e4c81e35b4a870fe6b9f8d58e with gcc (GCC) 8.1.0
kernel signature: e955928317960f35b09bbacbc711de3b2ea16056
run #0: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #1: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #2: crashed: general protection fault in bpf_skb_change_head
run #3: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #4: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #5: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #6: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #7: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #8: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #9: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
testing current HEAD e1f7d50ae3a3ec342e87a9b1ce6787bfb8b3c08b
testing commit e1f7d50ae3a3ec342e87a9b1ce6787bfb8b3c08b with gcc (GCC) 8.1.0
kernel signature: 975ae0df809414483010f8f2fdc01f3d9d16c9a4
run #0: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #1: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #2: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #3: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #4: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #5: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #6: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #7: crashed: KASAN: use-after-free Read in bpf_skb_change_head
run #8: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
run #9: crashed: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
revisions tested: 2, total time: 23m49.922390697s (build: 16m53.892545135s, test: 6m11.060701561s)
the crash still happens on HEAD
commit msg: Linux 4.14.160
crash: KASAN: slab-out-of-bounds Read in bpf_skb_change_head
IPv6: ADDRCONF(NETDEV_UP): veth0_to_hsr: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1_to_hsr: link is not ready
device hsr_slave_0 entered promiscuous mode
==================================================================
BUG: KASAN: slab-out-of-bounds in ____bpf_skb_change_head net/core/filter.c:2422 [inline]
BUG: KASAN: slab-out-of-bounds in bpf_skb_change_head+0x55e/0x6b0 net/core/filter.c:2419
Read of size 8 at addr ffff88806f42a450 by task syz-executor.0/6870

CPU: 0 PID: 6870 Comm: syz-executor.0 Not tainted 4.14.160-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+0xf7/0x13b lib/dump_stack.c:58
 print_address_description.cold.7+0x9/0x1c9 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report.cold.8+0x11a/0x2d3 mm/kasan/report.c:409
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 ____bpf_skb_change_head net/core/filter.c:2422 [inline]
 bpf_skb_change_head+0x55e/0x6b0 net/core/filter.c:2419
 bpf_prog_147a7bac71f62ca7+0x3ff/0x1000

Allocated by task 0:
(stack is not available)

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff88806f42a3c0
 which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 144 bytes inside of
 232-byte region [ffff88806f42a3c0, ffff88806f42a4a8)
The buggy address belongs to the page:
page:ffffea0001bd0a80 count:1 mapcount:0 mapping:ffff88806f42a000 index:0x0
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffff88806f42a000 0000000000000000 000000010000000c
raw: ffffea0001bd81a0 ffffea0002a11e60 ffff88821b75e540 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88806f42a300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88806f42a380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88806f42a400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                 ^
 ffff88806f42a480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88806f42a500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================