From: Dan Carpenter <dan.carpenter@oracle.com>
To: Jean Delvare <jdelvare@suse.de>
Cc: Daniel Kurtz <djkurtz@chromium.org>,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
syzbot <syzbot+ed71512d469895b5b34e@syzkaller.appspotmail.com>
Subject: Re: [PATCH] i2c: i801: Fix memory corruption in i801_isr_byte_done()
Date: Mon, 23 Mar 2020 12:37:33 +0300 [thread overview]
Message-ID: <20200323093733.GA26299@kadam> (raw)
In-Reply-To: <20200322231106.3d431ced@endymion>
On Sun, Mar 22, 2020 at 11:11:06PM +0100, Jean Delvare wrote:
> Definitely not correct. The first byte of the block data array MUST be
> the size of the block read. Even if the code above does not do the
> right thing, removing the line will not help.
>
Yeah. I misread the code.
> Is it possible that kasan got this wrong due to the convoluted logic?
> It's late and I'll check again tomorrow morning but the code looks OK
> to me.
KASan doesn't work like that. It works at runtime and doesn't care
about the logic.
https://syzkaller.appspot.com/bug?id=426fc8b1c1b63fb0af524d839dfcf452f2d858e2
At the bottom of the report it shows that we're in a field of f9
poisoned data so it's not priv->len which is wrong. (My patch was way
off).
mm/kasan/kasan.h:#define KASAN_VMALLOC_INVALID 0xF9 /* unallocated space in vmapped page */
The logic looks okay to me too. So possibly this was a race condition
or even memory corruption in an unrelated part of the kernel.
regards,
dan carpenter
next prev parent reply other threads:[~2020-03-23 9:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 6:34 KASAN: vmalloc-out-of-bounds Write in i801_isr syzbot
2020-01-14 7:34 ` [PATCH] i2c: i801: Fix memory corruption in i801_isr_byte_done() Dan Carpenter
2020-02-22 12:45 ` Wolfram Sang
2020-03-20 14:57 ` Wolfram Sang
2020-03-22 18:08 ` Jean Delvare
2020-03-22 21:10 ` Andy Shevchenko
2020-03-22 21:12 ` Wolfram Sang
2020-03-22 22:11 ` Jean Delvare
2020-03-23 9:37 ` Dan Carpenter [this message]
2020-03-23 17:51 ` Jean Delvare
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