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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: keescook@chromium.org, keescook@google.com
Cc: syzbot <syzbot+a3c9d2673837ccc0f22b@syzkaller.appspotmail.com>,
	crecklin@redhat.com, dvyukov@google.com, hpa@zytor.com,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	luto@kernel.org, mingo@redhat.com,
	syzkaller-bugs@googlegroups.com, tglx@linutronix.de,
	x86@kernel.org
Subject: Re: BUG: bad usercopy in __check_object_size (2)
Date: Sat, 8 Sep 2018 01:17:44 +0900	[thread overview]
Message-ID: <14d5bccf-f12d-0fc1-eddc-9fb24dc0cf14@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <000000000000e16cba057549aab6@google.com>

On 2018/09/08 0:29, syzbot wrote:
> syzbot has found a reproducer for the following crash on:
> 
> HEAD commit:A A A  28619527b8a7 Merge git://git.kernel.org/pub/scm/linux/kern..
> git tree:A A A A A A  bpf
> console output: https://syzkaller.appspot.com/x/log.txt?x=124e64d1400000
> kernel config:A  https://syzkaller.appspot.com/x/.config?x=62e9b447c16085cf
> dashboard link: https://syzkaller.appspot.com/bug?extid=a3c9d2673837ccc0f22b
> compiler:A A A A A A  gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro:A A A A A  https://syzkaller.appspot.com/x/repro.syz?x=179f9cd1400000
> C reproducer:A A  https://syzkaller.appspot.com/x/repro.c?x=11b3e8be400000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+a3c9d2673837ccc0f22b@syzkaller.appspotmail.com
> 
> A entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x440479
> usercopy: Kernel memory overwrite attempt detected to spans multiple pages (offset 0, size 64)!

Kees, is this because check_page_span() is failing to allow on-stack variable

   u8 opcodes[OPCODE_BUFSIZE];

which by chance crossed PAGE_SIZE boundary?

  reply	other threads:[~2018-09-07 16:18 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <000000000000edab9e0575497f40@google.com>
2018-09-07 15:29 ` syzbot
2018-09-07 16:17   ` Tetsuo Handa [this message]
2018-09-07 19:57     ` Kees Cook
2018-09-08 15:15       ` Dmitry Vyukov

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