From: Christian Eggers <ceggers@arri.de>
Date: Thu, 19 Nov 2020 11:09:06 +0000 (+0100)
Subject: net: dsa: avoid potential use-after-free error
X-Git-Tag: accepted/tizen/unified/20230118.172025~8321^2~206
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=30abc9cd9c6bdd44d23fc49a9c2526a86fba4305;p=platform%2Fkernel%2Flinux-rpi.git

net: dsa: avoid potential use-after-free error

If dsa_switch_ops::port_txtstamp() returns false, clone will be freed
immediately. Shouldn't store a pointer to freed memory.

Signed-off-by: Christian Eggers <ceggers@arri.de>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Tested-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20201119110906.25558-1-ceggers@arri.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index ff2266d..7efc753 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -522,10 +522,10 @@ static void dsa_skb_tx_timestamp(struct dsa_slave_priv *p,
 	if (!clone)
 		return;
 
-	DSA_SKB_CB(skb)->clone = clone;
-
-	if (ds->ops->port_txtstamp(ds, p->dp->index, clone, type))
+	if (ds->ops->port_txtstamp(ds, p->dp->index, clone, type)) {
+		DSA_SKB_CB(skb)->clone = clone;
 		return;
+	}
 
 	kfree_skb(clone);
 }