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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 ffff8801cd960680 by task syz-executor6/31858

CPU: 0 PID: 31858 Comm: syz-executor6 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 2392:
 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_node+0x144/0x780 mm/slab.c:3644
 __alloc_skb+0x111/0x780 net/core/skbuff.c:193
 alloc_skb include/linux/skbuff.h:987 [inline]
 alloc_uevent_skb+0x89/0x220 lib/kobject_uevent.c:288
 uevent_net_broadcast_untagged lib/kobject_uevent.c:324 [inline]
 kobject_uevent_net_broadcast lib/kobject_uevent.c:406 [inline]
 kobject_uevent_env+0x866/0x1110 lib/kobject_uevent.c:587
 kobject_synth_uevent+0xa4f/0xc0b lib/kobject_uevent.c:208
 uevent_store+0x26/0x70 drivers/base/core.c:993
 dev_attr_store+0x5e/0x90 drivers/base/core.c:713
 sysfs_kf_write+0x118/0x170 fs/sysfs/file.c:139
 kernfs_fop_write+0x2ba/0x480 fs/kernfs/file.c:316
 __vfs_write+0x10b/0x960 fs/read_write.c:485
 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

Freed by task 2392:
 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 net/core/skbuff.c:642 [inline]
 consume_skb+0x193/0x550 net/core/skbuff.c:701
 uevent_net_broadcast_untagged lib/kobject_uevent.c:335 [inline]
 kobject_uevent_net_broadcast lib/kobject_uevent.c:406 [inline]
 kobject_uevent_env+0x892/0x1110 lib/kobject_uevent.c:587
 kobject_synth_uevent+0xa4f/0xc0b lib/kobject_uevent.c:208
 uevent_store+0x26/0x70 drivers/base/core.c:993
 dev_attr_store+0x5e/0x90 drivers/base/core.c:713
 sysfs_kf_write+0x118/0x170 fs/sysfs/file.c:139
 kernfs_fop_write+0x2ba/0x480 fs/kernfs/file.c:316
 __vfs_write+0x10b/0x960 fs/read_write.c:485
 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 ffff8801cd960580
 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 [ffff8801cd960580, ffff8801cd960668)
The buggy address belongs to the page:
page:ffffea0007365800 count:1 mapcount:0 mapping:ffff8801cd960080 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801cd960080 0000000000000000 000000010000000c
raw: ffffea0007230760 ffffea0006e4eba0 ffff8801d9a11080 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cd960580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801cd960600: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
>ffff8801cd960680: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                   ^
 ffff8801cd960700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801cd960780: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
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