linux-kernel - [PATCH net-next] eth: fbnic: fix memory corruption in fbnic_tlv_attr_get

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Message-ID: <2791d4be-ade4-4e50-9b12-33307d8410f6@stanley.mountain>
Date: Fri, 7 Mar 2025 12:28:48 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Lee Trager <lee@...ger.us>
Cc: Alexander Duyck <alexanderduyck@...com>,
	Jakub Kicinski <kuba@...nel.org>, kernel-team@...a.com,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH net-next] eth: fbnic: fix memory corruption in
 fbnic_tlv_attr_get_string()

This code is trying to ensure that the last byte of the buffer is a NUL
terminator.  However, the problem is that attr->value[] is an array of
__le32, not char, so it zeroes out 4 bytes way beyond the end of the
buffer.  Cast the buffer to char to address this.

Fixes: e5cf5107c9e4 ("eth: fbnic: Update fbnic_tlv_attr_get_string() to work like nla_strscpy()")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 drivers/net/ethernet/meta/fbnic/fbnic_tlv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_tlv.c b/drivers/net/ethernet/meta/fbnic/fbnic_tlv.c
index d558d176e0df..517ed8b2f1cb 100644
--- a/drivers/net/ethernet/meta/fbnic/fbnic_tlv.c
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_tlv.c
@@ -261,7 +261,7 @@ ssize_t fbnic_tlv_attr_get_string(struct fbnic_tlv_msg *attr, char *dst,
 		return -E2BIG;
 
 	srclen = le16_to_cpu(attr->hdr.len) - sizeof(*attr);
-	if (srclen > 0 && attr->value[srclen - 1] == '\0')
+	if (srclen > 0 && ((char *)attr->value)[srclen - 1] == '\0')
 		srclen--;
 
 	if (srclen >= dstsize) {
-- 
2.47.2