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

From: Denis Efremov
Date: Mon Sep 30 2019 - 16:38:09 EST


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 <pontus.fuchs@xxxxxxxxx>
Cc: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: David Laight <David.Laight@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Denis Efremov <efremov@xxxxxxxxx>
---
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