From: syzbot <syzbot+c8504affd4fdd0c1b626@syzkaller.appspotmail.com>
To: ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: KASAN: use-after-free Read in skb_ensure_writable
Date: Sun, 03 Jun 2018 16:36:02 -0700 [thread overview]
Message-ID: <000000000000bab429056dc547be@google.com> (raw)
Hello,
syzbot found the following crash on:
HEAD commit: bcece5dc40b9 bpf: Change bpf_fib_lookup to return -EAFNOSU..
git tree: bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10ee76b7800000
kernel config: https://syzkaller.appspot.com/x/.config?x=e4078980b886800c
dashboard link: https://syzkaller.appspot.com/bug?extid=c8504affd4fdd0c1b626
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=10d926df800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1778c26f800000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c8504affd4fdd0c1b626@syzkaller.appspotmail.com
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
==================================================================
BUG: KASAN: use-after-free in pskb_may_pull include/linux/skbuff.h:2108
[inline]
BUG: KASAN: use-after-free in skb_ensure_writable+0x554/0x620
net/core/skbuff.c:5118
Read of size 4 at addr ffff8801b0b40fc0 by task syz-executor258/4479
CPU: 0 PID: 4479 Comm: syz-executor258 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
The buggy address belongs to the page:
page:ffffea0006c2d000 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: ffffea00075ea760 ffffea0006c39660 ffff8801b5848738 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8801b0b40e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff8801b0b40f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ffff8801b0b40f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff8801b0b41000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8801b0b41080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
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syzbot can test patches for this bug, for details see:
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next reply other threads:[~2018-06-03 23:36 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-03 23:36 syzbot [this message]
2018-06-08 9:53 ` KASAN: use-after-free Read in skb_ensure_writable Daniel Borkmann
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