Subject: [PATCH v2] ar5523: check NULL before memcpy() in ar5523_cmd()

From: Denis Efremov <[email-masked]>
Date: Mon, 30 Sep 2019 23:31:47 +0300

memcpy() call with "idata == NULL && ilen == 0" results in undefined
behavior in ar5523_cmd(). For example, NULL is passed in callchain
"ar5523_stat_work() -> ar5523_cmd_write() -> ar5523_cmd()". This patch
adds ilen check before memcpy() call in ar5523_cmd() to prevent an
undefined behavior.

Cc: Pontus Fuchs <[email-masked]>
Cc: Kalle Valo <[email-masked]>
Cc: "David S. Miller" <[email-masked]>
Cc: David Laight <[email-masked]>
Cc: [email-masked]
Signed-off-by: Denis Efremov <[email-masked]>
---
V2: check ilen instead of idata as suggested by David Laight.

 drivers/net/wireless/ath/ar5523/ar5523.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ar5523/ar5523.c b/drivers/net/wireless/ath/ar5523/ar5523.c
index b94759daeacc..da2d179430ca 100644
--- a/drivers/net/wireless/ath/ar5523/ar5523.c
+++ b/drivers/net/wireless/ath/ar5523/ar5523.c
@@ -255,7 +255,8 @@ static int ar5523_cmd(struct ar5523 *ar, u32 code, const void *idata,
 
 	if (flags & AR5523_CMD_FLAG_MAGIC)
 		hdr->magic = cpu_to_be32(1 << 24);
-	memcpy(hdr + 1, idata, ilen);
+	if (ilen)
+		memcpy(hdr + 1, idata, ilen);
 
 	cmd->odata = odata;
 	cmd->olen = olen;
-- 
2.21.0