From 4a36e160856db8a8ddd6a3d2e5db5a850ab87f82 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Mon, 14 Jun 2021 12:55:35 +0300
Subject: [PATCH] staging: gdm724x: check for buffer overflow in gdm_lte_multi_sdu_pkt()
Git-commit: 4a36e160856db8a8ddd6a3d2e5db5a850ab87f82
Patch-mainline: v5.14-rc1
References: git-fixes

There needs to be a check to verify that we don't read beyond the end
of "buf".  This function is called from do_rx().  The "buf" is the USB
transfer_buffer and "len" is "urb->actual_length".

Fixes: 61e121047645 ("staging: gdm7240: adding LTE USB driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YMcnl4zCwGWGDVMG@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/staging/gdm724x/gdm_lte.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/staging/gdm724x/gdm_lte.c
+++ b/drivers/staging/gdm724x/gdm_lte.c
@@ -680,6 +680,7 @@ static void gdm_lte_multi_sdu_pkt(struct
 	struct sdu *sdu = NULL;
 	struct gdm_endian *endian = phy_dev->get_endian(phy_dev->priv_dev);
 	u8 *data = (u8 *)multi_sdu->data;
+	int copied;
 	u16 i = 0;
 	u16 num_packet;
 	u16 hci_len;
@@ -691,6 +692,12 @@ static void gdm_lte_multi_sdu_pkt(struct
 	num_packet = gdm_dev16_to_cpu(endian, multi_sdu->num_packet);
 
 	for (i = 0; i < num_packet; i++) {
+		copied = data - multi_sdu->data;
+		if (len < copied + sizeof(*sdu)) {
+			pr_err("rx prevent buffer overflow");
+			return;
+		}
+
 		sdu = (struct sdu *)data;
 
 		cmd_evt  = gdm_dev16_to_cpu(endian, sdu->cmd_evt);
@@ -701,7 +708,8 @@ static void gdm_lte_multi_sdu_pkt(struct
 			pr_err("rx sdu wrong hci %04x\n", cmd_evt);
 			return;
 		}
-		if (hci_len < 12) {
+		if (hci_len < 12 ||
+		    len < copied + sizeof(*sdu) + (hci_len - 12)) {
 			pr_err("rx sdu invalid len %d\n", hci_len);
 			return;
 		}