stlinkv3_spi: Avoid division by zero

Change-Id: I08c0612f3fea59add9bde2fb3cc5c4b5c3756516
Found-by: Coverity Scan #1412744
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/40653
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/67864
Reviewed-by: Felix Singer <felixsinger@posteo.net>
---
M stlinkv3_spi.c
1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/stlinkv3_spi.c b/stlinkv3_spi.c
index 7338911..d2988b6 100644
--- a/stlinkv3_spi.c
+++ b/stlinkv3_spi.c
@@ -491,10 +491,11 @@
 	speed_str = extract_programmer_param("spispeed");
 	if (speed_str) {
 		sck_freq_kHz = strtoul(speed_str, &endptr, 0);
-		if (*endptr) {
+		if (*endptr || sck_freq_kHz == 0) {
 			msg_perr("The spispeed parameter passed with invalid format: %s\n",
 				 speed_str);
-			msg_perr("Please pass the parameter with a simple number in kHz\n");
+			msg_perr("Please pass the parameter "
+				 "with a simple non-zero number in kHz\n");
 			return -1;
 		}
 		free(speed_str);

