[PATCH v2 3/3] ussd: ensure ussd content fits in buffers

["Sicelo A. Mhlongo" <absicsz@gmail.com>]

Fixes: CVE-2024-7539
---
 drivers/atmodem/ussd.c      | 5 ++++-
 drivers/huaweimodem/ussd.c  | 5 ++++-
 drivers/speedupmodem/ussd.c | 5 ++++-
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/atmodem/ussd.c b/drivers/atmodem/ussd.c
index 32a9fe91..59dd2e59 100644
--- a/drivers/atmodem/ussd.c
+++ b/drivers/atmodem/ussd.c
@@ -93,7 +93,7 @@ static void cusd_parse(GAtResult *result, struct ofono_ussd *ussd)
 	const char *content;
 	int dcs;
 	enum sms_charset charset;
-	unsigned char msg[160];
+	unsigned char msg[160] = {0};
 	const unsigned char *msg_ptr = NULL;
 	long msg_len;
 
@@ -113,6 +113,9 @@ static void cusd_parse(GAtResult *result, struct ofono_ussd *ussd)
 	if (!g_at_result_iter_next_number(&iter, &dcs))
 		dcs = 0;
 
+	if (strlen(content) > sizeof(msg) * 2)
+		goto out;
+
 	if (!cbs_dcs_decode(dcs, NULL, NULL, &charset, NULL, NULL, NULL)) {
 		ofono_error("Unsupported USSD data coding scheme (%02x)", dcs);
 		status = 4; /* Not supported */
diff --git a/drivers/huaweimodem/ussd.c b/drivers/huaweimodem/ussd.c
index 5e1c9078..3d165c87 100644
--- a/drivers/huaweimodem/ussd.c
+++ b/drivers/huaweimodem/ussd.c
@@ -38,7 +38,7 @@ static void cusd_parse(GAtResult *result, struct ofono_ussd *ussd)
 	int status;
 	int dcs = 0;
 	const char *content;
-	unsigned char msg[160];
+	unsigned char msg[160] = {0};
 	const unsigned char *msg_ptr = NULL;
 	long msg_len;
 
@@ -55,6 +55,9 @@ static void cusd_parse(GAtResult *result, struct ofono_ussd *ussd)
 
 	g_at_result_iter_next_number(&iter, &dcs);
 
+	if (strlen(content) > sizeof(msg) * 2)
+		goto out;
+
 	msg_ptr = decode_hex_own_buf(content, -1, &msg_len, 0, msg);
 
 out:
diff --git a/drivers/speedupmodem/ussd.c b/drivers/speedupmodem/ussd.c
index aafa4bc9..a5efde0c 100644
--- a/drivers/speedupmodem/ussd.c
+++ b/drivers/speedupmodem/ussd.c
@@ -37,7 +37,7 @@ static void cusd_parse(GAtResult *result, struct ofono_ussd *ussd)
 	int status;
 	int dcs = 0;
 	const char *content;
-	unsigned char msg[160];
+	unsigned char msg[160] = {0};
 	const unsigned char *msg_ptr = NULL;
 	long msg_len;
 
@@ -54,6 +54,9 @@ static void cusd_parse(GAtResult *result, struct ofono_ussd *ussd)
 
 	g_at_result_iter_next_number(&iter, &dcs);
 
+	if (strlen(content) > sizeof(msg) * 2)
+		goto out;
+
 	msg_ptr = decode_hex_own_buf(content, -1, &msg_len, 0, msg);
 
 out:
-- 
2.45.2