linux-kernel - [PATCH 4.4 110/162] ar5523: check NULL before memcpy() in ar5523

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Date:   Thu, 19 Dec 2019 19:33:38 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Pontus Fuchs <pontus.fuchs@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        David Laight <David.Laight@...LAB.COM>,
        Denis Efremov <efremov@...ux.com>
Subject: [PATCH 4.4 110/162] ar5523: check NULL before memcpy() in ar5523_cmd()

From: Denis Efremov <efremov@...ux.com>

commit 315cee426f87658a6799815845788fde965ddaad upstream.

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@...il.com>
Cc: Kalle Valo <kvalo@...eaurora.org>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: David Laight <David.Laight@...LAB.COM>
Cc: stable@...r.kernel.org
Signed-off-by: Denis Efremov <efremov@...ux.com>
Signed-off-by: Kalle Valo <kvalo@...eaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- 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,

 	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;