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BUG: KASAN: slab-out-of-bounds in pskb_may_pull include/linux/skbuff.h:2106 [inline]
BUG: KASAN: slab-out-of-bounds in skb_ensure_writable+0x554/0x620 net/core/skbuff.c:5118
Read of size 4 at addr ffff8801b25ae140 by task syz-executor2/9754

CPU: 1 PID: 9754 Comm: syz-executor2 Not tainted 4.17.0-rc7+ #38
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+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 pskb_may_pull include/linux/skbuff.h:2106 [inline]
 skb_ensure_writable+0x554/0x620 net/core/skbuff.c:5118
 __bpf_try_make_writable net/core/filter.c:1606 [inline]
 bpf_try_make_writable net/core/filter.c:1612 [inline]
 ____bpf_l4_csum_replace net/core/filter.c:1822 [inline]
 bpf_l4_csum_replace+0x91/0x4a0 net/core/filter.c:1809

Allocated by task 4507:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
 __build_skb+0xa3/0x410 net/core/skbuff.c:281
 __napi_alloc_skb+0x19a/0x300 net/core/skbuff.c:482
 napi_alloc_skb include/linux/skbuff.h:2650 [inline]
 page_to_skb.isra.38+0xe6/0x8c0 drivers/net/virtio_net.c:355
 receive_mergeable+0x1413/0x38a0 drivers/net/virtio_net.c:858
 receive_buf+0xca1/0x2bb0 drivers/net/virtio_net.c:963
 virtnet_receive drivers/net/virtio_net.c:1246 [inline]
 virtnet_poll+0x3c8/0xdb5 drivers/net/virtio_net.c:1328
 napi_poll net/core/dev.c:5789 [inline]
 net_rx_action+0x7b7/0x1930 net/core/dev.c:5855
 __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285

Freed by task 4507:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x86/0x2d0 mm/slab.c:3756
 kfree_skbmem+0x13c/0x210 net/core/skbuff.c:582
 __kfree_skb+0x1d/0x20 net/core/skbuff.c:642
 tcp_rcv_established+0x144c/0x2050 net/ipv4/tcp_input.c:5476
 tcp_v4_do_rcv+0x5ad/0x850 net/ipv4/tcp_ipv4.c:1518
 sk_backlog_rcv include/net/sock.h:914 [inline]
 __release_sock+0x12f/0x3a0 net/core/sock.c:2355
 release_sock+0xa4/0x2b0 net/core/sock.c:2870
 tcp_sendmsg+0x3a/0x50 net/ipv4/tcp.c:1448
 inet_sendmsg+0x19f/0x690 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:629 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:639
 sock_write_iter+0x35a/0x5a0 net/socket.c:908
 call_write_iter include/linux/fs.h:1784 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x64d/0x960 fs/read_write.c:487
 vfs_write+0x1f8/0x560 fs/read_write.c:549
 ksys_write+0xf9/0x250 fs/read_write.c:598
 __do_sys_write fs/read_write.c:610 [inline]
 __se_sys_write fs/read_write.c:607 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:607
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801b25ae040
 which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 24 bytes to the right of
 232-byte region [ffff8801b25ae040, ffff8801b25ae128)
The buggy address belongs to the page:
page:ffffea0006c96b80 count:1 mapcount:0 mapping:ffff8801b25ae040 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801b25ae040 0000000000000000 000000010000000c
raw: ffffea0006e02220 ffffea0006c6d9e0 ffff8801d9bdd6c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801b25ae000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8801b25ae080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801b25ae100: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
                                           ^
 ffff8801b25ae180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801b25ae200: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
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