[PATCH 4.19 203/421] staging: gdm724x: check for overflow in gdm_lte_netif_rx()

Greg Kroah-Hartman
2021-07-19T16:26:29Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 7002b526f4ff1f6da34356e67085caafa6be383a ]

This code assumes that "len" is at least 62 bytes, but we need a check
to prevent a read overflow.

Fixes: 61e121047645 ("staging: gdm7240: adding LTE USB driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YMcoTPsCYlhh2TQo@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/staging/gdm724x/gdm_lte.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/gdm724x/gdm_lte.c b/drivers/staging/gdm724x/gdm_lte.c
index 25135980349a..3c537807f4d1 100644
--- a/drivers/staging/gdm724x/gdm_lte.c
+++ b/drivers/staging/gdm724x/gdm_lte.c
@@ -611,10 +611,12 @@ static void gdm_lte_netif_rx(struct net_device *dev, char *buf,
* bytes (99,130,83,99 dec)
*/
} __packed;
- void *addr = buf + sizeof(struct iphdr) +
- sizeof(struct udphdr) +
- offsetof(struct dhcp_packet, chaddr);
- ether_addr_copy(nic->dest_mac_addr, addr);
+ int offset = sizeof(struct iphdr) +
+ sizeof(struct udphdr) +
+ offsetof(struct dhcp_packet, chaddr);
+ if (offset + ETH_ALEN > len)
+ return;
+ ether_addr_copy(nic->dest_mac_addr, buf + offset);
}
}

--
2.30.2