diff mbox

[RFC,5/7] wlcore: avoid fragile snprintf use

Message ID 1457469654-17059-6-git-send-email-linux@rasmusvillemoes.dk (mailing list archive)
State RFC
Delegated to: Kalle Valo
Headers show

Commit Message

Rasmus Villemoes March 8, 2016, 8:40 p.m. UTC 
Appending to a buffer like this is not guaranteed to work (passing
overlapping src and dst buffers to snprintf is undefined
behaviour). The standard and safe idiom is to keep track of the
current string length.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/net/wireless/ti/wlcore/boot.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

Comments

Kalle Valo March 9, 2016, 11:49 a.m. UTC | #1 
Rasmus Villemoes <linux@rasmusvillemoes.dk> writes:

> Appending to a buffer like this is not guaranteed to work (passing
> overlapping src and dst buffers to snprintf is undefined
> behaviour). The standard and safe idiom is to keep track of the
> current string length.
>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>

Should I take this or what's the plan?
diff mbox

Patch

diff --git a/drivers/net/wireless/ti/wlcore/boot.c b/drivers/net/wireless/ti/wlcore/boot.c
index 19b7ec7b69c2..401d75c02bf4 100644
--- a/drivers/net/wireless/ti/wlcore/boot.c
+++ b/drivers/net/wireless/ti/wlcore/boot.c
@@ -86,7 +86,7 @@  static int wlcore_validate_fw_ver(struct wl1271 *wl)
 	unsigned int *min_ver = (wl->fw_type == WL12XX_FW_TYPE_MULTI) ?
 		wl->min_mr_fw_ver : wl->min_sr_fw_ver;
 	char min_fw_str[32] = "";
-	int i;
+	int i, len;
 
 	/* the chip must be exactly equal */
 	if ((min_ver[FW_VER_CHIP] != WLCORE_FW_VER_IGNORE) &&
@@ -119,13 +119,15 @@  static int wlcore_validate_fw_ver(struct wl1271 *wl)
 	return 0;
 
 fail:
+	len = 0;
 	for (i = 0; i < NUM_FW_VER; i++)
 		if (min_ver[i] == WLCORE_FW_VER_IGNORE)
-			snprintf(min_fw_str, sizeof(min_fw_str),
-				  "%s*.", min_fw_str);
+			len += scnprintf(min_fw_str + len,
+					 sizeof(min_fw_str) - len, "*.");
 		else
-			snprintf(min_fw_str, sizeof(min_fw_str),
-				  "%s%u.", min_fw_str, min_ver[i]);
+			len += scnprintf(min_fw_str + len,
+					 sizeof(min_fw_str) - len,
+					 "%u.", min_ver[i]);
 
 	wl1271_error("Your WiFi FW version (%u.%u.%u.%u.%u) is invalid.\n"
 		     "Please use at least FW %s\n"