lkml.org 
[lkml]   [2020]   [Jul]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1/2] Smack: fix another vsscanf out of bounds
From
Date
On 7/23/2020 8:22 AM, Dan Carpenter wrote:
> This is similar to commit 84e99e58e8d1 ("Smack: slab-out-of-bounds in
> vsscanf") where we added a bounds check on "rule".
>
> Reported-by: syzbot+a22c6092d003d6fe1122@syzkaller.appspotmail.com
> Fixes: f7112e6c9abf ("Smack: allow for significantly longer Smack labels v4")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Thanks. I'll be testing these and take them assuming they pass.

> ---
> This check is very straight forward and should fix the bug. But if you
> look at the fixes tag we used to rely on the check:
>
> if (count != (SMK_CIPSOMIN + catlen * SMK_DIGITLEN))
>
> and now that has been changed to:
>
> if (format == SMK_FIXED24_FMT &&
> count != (SMK_CIPSOMIN + catlen * SMK_DIGITLEN))
> goto out;
>
> so it doesn't apply for every format.
>
> security/smack/smackfs.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
> index c21b656b3263..81c6ceeaa4f9 100644
> --- a/security/smack/smackfs.c
> +++ b/security/smack/smackfs.c
> @@ -905,6 +905,10 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
>
> for (i = 0; i < catlen; i++) {
> rule += SMK_DIGITLEN;
> + if (rule > data + count) {
> + rc = -EOVERFLOW;
> + goto out;
> + }
> ret = sscanf(rule, "%u", &cat);
> if (ret != 1 || cat > SMACK_CIPSO_MAXCATNUM)
> goto out;

\
 
 \ /
  Last update: 2020-07-23 18:39    [W:2.429 / U:0.096 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site