[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20200203161917.810156004@linuxfoundation.org>
Date: Mon, 3 Feb 2020 16:18:52 +0000
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Andrey Shvetsov <andrey.shvetsov@....de>
Subject: [PATCH 4.14 07/89] staging: most: net: fix buffer overflow
From: Andrey Shvetsov <andrey.shvetsov@....de>
commit 4d1356ac12f4d5180d0df345d85ff0ee42b89c72 upstream.
If the length of the socket buffer is 0xFFFFFFFF (max size for an
unsigned int), then payload_len becomes 0xFFFFFFF1 after subtracting 14
(ETH_HLEN). Then, mdp_len is set to payload_len + 16 (MDP_HDR_LEN)
which overflows and results in a value of 2. These values for
payload_len and mdp_len will pass current buffer size checks.
This patch checks if derived from skb->len sum may overflow.
The check is based on the following idea:
For any `unsigned V1, V2` and derived `unsigned SUM = V1 + V2`,
`V1 + V2` overflows iif `SUM < V1`.
Reported-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Andrey Shvetsov <andrey.shvetsov@....de>
Cc: stable <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20200116172238.6046-1-andrey.shvetsov@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/staging/most/aim-network/networking.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/drivers/staging/most/aim-network/networking.c
+++ b/drivers/staging/most/aim-network/networking.c
@@ -85,6 +85,11 @@ static int skb_to_mamac(const struct sk_
unsigned int payload_len = skb->len - ETH_HLEN;
unsigned int mdp_len = payload_len + MDP_HDR_LEN;
+ if (mdp_len < skb->len) {
+ pr_err("drop: too large packet! (%u)\n", skb->len);
+ return -EINVAL;
+ }
+
if (mbo->buffer_length < mdp_len) {
pr_err("drop: too small buffer! (%d for %d)\n",
mbo->buffer_length, mdp_len);
@@ -132,6 +137,11 @@ static int skb_to_mep(const struct sk_bu
u8 *buff = mbo->virt_address;
unsigned int mep_len = skb->len + MEP_HDR_LEN;
+ if (mep_len < skb->len) {
+ pr_err("drop: too large packet! (%u)\n", skb->len);
+ return -EINVAL;
+ }
+
if (mbo->buffer_length < mep_len) {
pr_err("drop: too small buffer! (%d for %d)\n",
mbo->buffer_length, mep_len);
Powered by blists - more mailing lists