diff mbox

[PULL,2/2] slirp: check len against dhcp options array end

Message ID 20170802222607.32085-3-samuel.thibault@ens-lyon.org
State New
Headers show

Commit Message

Samuel Thibault Aug. 2, 2017, 10:26 p.m. UTC 
From: Prasad J Pandit <pjp@fedoraproject.org>

While parsing dhcp options string in 'dhcp_decode', if an options'
length 'len' appeared towards the end of 'bp_vend' array, ensuing
read could lead to an OOB memory access issue. Add check to avoid it.

Reported-by: Reno Robert <renorobert@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
---
 slirp/bootp.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Samuel Thibault Aug. 2, 2017, 10:27 p.m. UTC | #1 
Samuel Thibault, on jeu. 03 août 2017 00:26:07 +0200, wrote:
> From: Prasad J Pandit <pjp@fedoraproject.org>
> 
> While parsing dhcp options string in 'dhcp_decode', if an options'
> length 'len' appeared towards the end of 'bp_vend' array, ensuing
> read could lead to an OOB memory access issue. Add check to avoid it.
> 
> Reported-by: Reno Robert <renorobert@gmail.com>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

Oops, this should have mentioned the CVE, I'll redo the pull request,
sorry.

> ---
>  slirp/bootp.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/slirp/bootp.c b/slirp/bootp.c
> index 5a4646c182..5dd1a415b5 100644
> --- a/slirp/bootp.c
> +++ b/slirp/bootp.c
> @@ -123,6 +123,9 @@ static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
>              if (p >= p_end)
>                  break;
>              len = *p++;
> +            if (p + len > p_end) {
> +                break;
> +            }
>              DPRINTF("dhcp: tag=%d len=%d\n", tag, len);
>  
>              switch(tag) {
> -- 
> 2.13.2
>
diff mbox

Patch

diff --git a/slirp/bootp.c b/slirp/bootp.c
index 5a4646c182..5dd1a415b5 100644
--- a/slirp/bootp.c
+++ b/slirp/bootp.c
@@ -123,6 +123,9 @@  static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
             if (p >= p_end)
                 break;
             len = *p++;
+            if (p + len > p_end) {
+                break;
+            }
             DPRINTF("dhcp: tag=%d len=%d\n", tag, len);
 
             switch(tag) {