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BUG: KASAN: slab-out-of-bounds in pskb_may_pull include/linux/skbuff.h:2108 [inline]
BUG: KASAN: slab-out-of-bounds in skb_ensure_writable+0x554/0x620 net/core/skbuff.c:5118
Read of size 4 at addr ffff8801ba17df40 by task syz-executor1/7525

CPU: 0 PID: 7525 Comm: syz-executor1 Not tainted 4.17.0-rc6+ #29
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:2108 [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_l3_csum_replace net/core/filter.c:1774 [inline]
 bpf_l3_csum_replace+0x8c/0x4d0 net/core/filter.c:1765

Allocated by task 6606:
 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
 getname_flags+0xd0/0x5a0 fs/namei.c:140
 user_path_at_empty+0x2d/0x50 fs/namei.c:2555
 user_path_at include/linux/namei.h:57 [inline]
 vfs_statx+0x121/0x1f0 fs/stat.c:185
 vfs_lstat include/linux/fs.h:3083 [inline]
 __do_sys_newlstat+0x87/0xf0 fs/stat.c:350
 __se_sys_newlstat fs/stat.c:344 [inline]
 __x64_sys_newlstat+0x54/0x80 fs/stat.c:344
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6606:
 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
 putname+0xf2/0x130 fs/namei.c:261
 filename_lookup+0x38b/0x4f0 fs/namei.c:2330
 user_path_at_empty+0x40/0x50 fs/namei.c:2555
 user_path_at include/linux/namei.h:57 [inline]
 vfs_statx+0x121/0x1f0 fs/stat.c:185
 vfs_lstat include/linux/fs.h:3083 [inline]
 __do_sys_newlstat+0x87/0xf0 fs/stat.c:350
 __se_sys_newlstat fs/stat.c:344 [inline]
 __x64_sys_newlstat+0x54/0x80 fs/stat.c:344
 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 ffff8801ba17c340
 which belongs to the cache names_cache of size 4096
The buggy address is located 3072 bytes to the right of
 4096-byte region [ffff8801ba17c340, ffff8801ba17d340)
The buggy address belongs to the page:
page:ffffea0006e85f00 count:1 mapcount:0 mapping:ffff8801ba17c340 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801ba17c340 0000000000000000 0000000100000001
raw: ffffea00072e2da0 ffffea00072d0da0 ffff8801da988dc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ba17de00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801ba17de80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801ba17df00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                           ^
 ffff8801ba17df80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801ba17e000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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