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Miller" , Jakub Kicinski , , , Christian Eggers Subject: [PATCH net-next v2] net: dsa: avoid potential use-after-free error Date: Thu, 19 Nov 2020 12:09:06 +0100 Message-ID: <20201119110906.25558-1-ceggers@arri.de> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [192.168.54.113] X-RMX-ID: 20201119-120914-4CcH4V2sdZz2TTJR-0@kdin02 X-RMX-SOURCE: 217.111.95.66 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Fixes: 146d442c2357 ("net: dsa: Keep a pointer to the skb clone for TX timestamping") --- Changes since v1: - Fixed "Fixes:" tag (and configured my GIT) - Adjusted commit description net/dsa/slave.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/net/dsa/slave.c b/net/dsa/slave.c index ff2266d2b998..7efc753e4d9d 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); } -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. 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