blob: bdf45e9954a4b39370f5a9c6ceb35a17557b0888 [file] [log] [blame]
From 9beecb18e4b2ed50868edf85baad83d9455c0f01 Mon Sep 17 00:00:00 2001
From: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Date: Thu, 16 Jan 2020 18:22:39 +0100
Subject: [PATCH] staging: most: net: fix buffer overflow
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@linuxfoundation.org>
Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200116172238.6046-1-andrey.shvetsov@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/staging/most/net/net.c b/drivers/staging/most/net/net.c
index c8a64e209027..cc680c08c342 100644
--- a/drivers/staging/most/net/net.c
+++ b/drivers/staging/most/net/net.c
@@ -81,6 +81,11 @@ static int skb_to_mamac(const struct sk_buff *skb, struct mbo *mbo)
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);
@@ -128,6 +133,11 @@ static int skb_to_mep(const struct sk_buff *skb, struct mbo *mbo)
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);
--
2.7.4