From: Dan Carpenter <dan.carpenter@oracle.com>
To: Hyunwoo Kim <imv4bel@gmail.com>,
deller@gmx.de, linux-fbdev@vger.kernel.org,
Masami Ichikawa <masami.ichikawa@miraclelinux.com>,
cip-dev <cip-dev@lists.cip-project.org>,
Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Subject: Re: [PATCH] pxa3xx-gcu: Fix integer overflow in pxa3xx_gcu_write
Date: Tue, 20 Sep 2022 09:02:34 +0300 [thread overview]
Message-ID: <YylXes0RnFv97uKU@kili> (raw)
On Mon, Jun 20, 2022 at 07:00:10AM -0700, Hyunwoo Kim wrote:
> In pxa3xx_gcu_write, a count parameter of
> type size_t is passed to words of type int.
> Then, copy_from_user may cause a heap overflow because
> it is used as the third argument of copy_from_user.
>
> Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
> ---
> drivers/video/fbdev/pxa3xx-gcu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/pxa3xx-gcu.c b/drivers/video/fbdev/pxa3xx-gcu.c
> index 043cc8f9ef1c..c3cd1e1cc01b 100644
> --- a/drivers/video/fbdev/pxa3xx-gcu.c
> +++ b/drivers/video/fbdev/pxa3xx-gcu.c
> @@ -381,7 +381,7 @@ pxa3xx_gcu_write(struct file *file, const char *buff,
> struct pxa3xx_gcu_batch *buffer;
> struct pxa3xx_gcu_priv *priv = to_pxa3xx_gcu_priv(file);
>
> - int words = count / 4;
> + size_t words = count / 4;
The count variable is actually capped at MAX_RW_COUNT in vfs_write()
so "words" cannot be negative. This patch helps clean up the code but
it does not affect run time.
This is CVE-2022-39842.
regards,
dan carpenter
PS: The other relavant code for people looking for integer overflows in
read/write functions is in rw_verify_area(). That function prevents a
lot of suspicious looking driver code from being exploitable.
next reply other threads:[~2022-09-20 6:03 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-20 6:02 Dan Carpenter [this message]
2022-09-20 6:13 ` [PATCH] pxa3xx-gcu: Fix integer overflow in pxa3xx_gcu_write Dan Carpenter
2022-09-20 6:22 ` Hyunwoo Kim
2022-09-20 7:12 ` Dan Carpenter
-- strict thread matches above, loose matches on Subject: below --
2022-06-11 19:28 Hyunwoo Kim
2022-06-20 12:50 ` Helge Deller
2022-06-20 14:17 ` Hyunwoo Kim
2022-06-20 18:13 ` Helge Deller
2022-06-20 18:16 ` Hyunwoo Kim
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