From: Bingbu Cao <bingbu.cao@linux.intel.com>
To: Sakari Ailus <sakari.ailus@linux.intel.com>, linux-media@vger.kernel.org
Cc: Arnd Bergmann <arnd@kernel.org>,
syzbot <syzbot+1115e79c8df6472c612b@syzkaller.appspotmail.com>,
Arnd Bergmann <arnd@arndb.de>,
Hans Verkuil <hverkuil-cisco@xs4all.nl>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: [PATCH v2 1/1] v4l: ioctl: Fix memory leak in video_usercopy
Date: Thu, 14 Jan 2021 12:50:32 +0800 [thread overview]
Message-ID: <29c100a1-cfea-9312-1d83-2d3b0c1c02d4@linux.intel.com> (raw)
In-Reply-To: <20201220201124.13688-1-sakari.ailus@linux.intel.com>
Sakari,
On 12/21/20 4:11 AM, Sakari Ailus wrote:
> When an IOCTL with argument size larger than 128 that also used array
> arguments were handled, two memory allocations were made but alas, only
> the latter one of them was released. This happened because there was only
> a single local variable to hold such a temporary allocation.
>
> Fix this by adding separate variables to hold the pointers to the
> temporary allocations.
>
> Reported-by: Arnd Bergmann <arnd@kernel.org>
> Reported-by: syzbot+1115e79c8df6472c612b@syzkaller.appspotmail.com
> Fixes: d14e6d76ebf7 ("[media] v4l: Add multi-planar ioctl handling code")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
> drivers/media/v4l2-core/v4l2-ioctl.c | 32 ++++++++++++----------------
> 1 file changed, 14 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index 3198abdd538c..9906b41004e9 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -3283,7 +3283,7 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg,
> v4l2_kioctl func)
> {
> char sbuf[128];
> - void *mbuf = NULL;
> + void *mbuf = NULL, *array_buf = NULL;
> void *parg = (void *)arg;
> long err = -EINVAL;
> bool has_array_args;
> @@ -3318,27 +3318,21 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg,
> has_array_args = err;
>
> if (has_array_args) {
> - /*
> - * When adding new types of array args, make sure that the
> - * parent argument to ioctl (which contains the pointer to the
> - * array) fits into sbuf (so that mbuf will still remain
> - * unused up to here).
> - */
> - mbuf = kvmalloc(array_size, GFP_KERNEL);
> + array_buf = kvmalloc(array_size, GFP_KERNEL);
> err = -ENOMEM;
> - if (NULL == mbuf)
> + if (array_buf == NULL)
if (!array_buf)
?
> goto out_array_args;
> err = -EFAULT;
> if (in_compat_syscall())
> - err = v4l2_compat_get_array_args(file, mbuf, user_ptr,
> - array_size, orig_cmd,
> - parg);
> + err = v4l2_compat_get_array_args(file, array_buf,
> + user_ptr, array_size,
> + orig_cmd, parg);
> else
> - err = copy_from_user(mbuf, user_ptr, array_size) ?
> + err = copy_from_user(array_buf, user_ptr, array_size) ?
> -EFAULT : 0;
> if (err)
> goto out_array_args;
> - *kernel_ptr = mbuf;
> + *kernel_ptr = array_buf;
> }
>
> /* Handles IOCTL */
> @@ -3360,12 +3354,13 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg,
> if (in_compat_syscall()) {
> int put_err;
>
> - put_err = v4l2_compat_put_array_args(file, user_ptr, mbuf,
> - array_size, orig_cmd,
> - parg);
> + put_err = v4l2_compat_put_array_args(file, user_ptr,
> + array_buf,
> + array_size,
> + orig_cmd, parg);
> if (put_err)
> err = put_err;
> - } else if (copy_to_user(user_ptr, mbuf, array_size)) {
> + } else if (copy_to_user(user_ptr, array_buf, array_size)) {
> err = -EFAULT;
> }
> goto out_array_args;
> @@ -3381,6 +3376,7 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg,
> if (video_put_user((void __user *)arg, parg, cmd, orig_cmd))
> err = -EFAULT;
> out:
> + kvfree(array_buf);
> kvfree(mbuf);
> return err;
> }
>
--
Best regards,
Bingbu Cao
next prev parent reply other threads:[~2021-01-14 4:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-20 20:11 [PATCH v2 1/1] v4l: ioctl: Fix memory leak in video_usercopy Sakari Ailus
2021-01-14 4:50 ` Bingbu Cao [this message]
2021-01-14 4:59 ` Bingbu Cao
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=29c100a1-cfea-9312-1d83-2d3b0c1c02d4@linux.intel.com \
--to=bingbu.cao@linux.intel.com \
--cc=arnd@arndb.de \
--cc=arnd@kernel.org \
--cc=hverkuil-cisco@xs4all.nl \
--cc=laurent.pinchart@ideasonboard.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=mchehab@kernel.org \
--cc=sakari.ailus@linux.intel.com \
--cc=syzbot+1115e79c8df6472c612b@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).