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From:   Artem Chernyshev <artem.chernyshev@red-soft.ru>
To:     Vladimir Oltean <olteanv@gmail.com>,
        Woojung Huh <woojung.huh@microchip.com>
Cc:     Artem Chernyshev <artem.chernyshev@red-soft.ru>,
        Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        "David S . Miller" <davem@davemloft.net>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org
Subject: [PATCH v2] net: dsa: Check return value from skb_trim_rcsum()
Date:   Tue, 29 Nov 2022 22:43:09 +0300
Message-Id: <20221129194309.3428340-1-artem.chernyshev@red-soft.ru>
In-Reply-To: <20221129165531.wgeyxgo5el2x43mj@skbuf>
References: 
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Return NULL if we got unexpected value from skb_trim_rcsum()

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 01ef09caad66 ("net: dsa: Add tag handling for Hirschmann Hellcreek switches")
Fixes: bafe9ba7d908 ("net: dsa: ksz: Factor out common tag code")
Fixes: 4913b8ebf8a9 ("net: dsa: add support for the SJA1110 native tagging protocol")
Signed-off-by: Artem Chernyshev <artem.chernyshev@red-soft.ru>
---
V1->V2 Fixes for tag_hellcreek.c and tag_sja1105.c

 net/dsa/tag_hellcreek.c | 3 ++-
 net/dsa/tag_ksz.c       | 3 ++-
 net/dsa/tag_sja1105.c   | 3 ++-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/dsa/tag_hellcreek.c b/net/dsa/tag_hellcreek.c
index 846588c0070a..53a206d11685 100644
--- a/net/dsa/tag_hellcreek.c
+++ b/net/dsa/tag_hellcreek.c
@@ -49,7 +49,8 @@ static struct sk_buff *hellcreek_rcv(struct sk_buff *skb,
 		return NULL;
 	}
 
-	pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN);
+	if (pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN))
+		return NULL;
 
 	dsa_default_offload_fwd_mark(skb);
 
diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 38fa19c1e2d5..429250298ac4 100644
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c
@@ -21,7 +21,8 @@ static struct sk_buff *ksz_common_rcv(struct sk_buff *skb,
 	if (!skb->dev)
 		return NULL;
 
-	pskb_trim_rcsum(skb, skb->len - len);
+	if (pskb_trim_rcsum(skb, skb->len - len))
+		return NULL;
 
 	dsa_default_offload_fwd_mark(skb);
 
diff --git a/net/dsa/tag_sja1105.c b/net/dsa/tag_sja1105.c
index 83e4136516b0..1a85125bda6d 100644
--- a/net/dsa/tag_sja1105.c
+++ b/net/dsa/tag_sja1105.c
@@ -665,7 +665,8 @@ static struct sk_buff *sja1110_rcv_inband_control_extension(struct sk_buff *skb,
 		 * padding and trailer we need to account for the fact that
 		 * skb->data points to skb_mac_header(skb) + ETH_HLEN.
 		 */
-		pskb_trim_rcsum(skb, start_of_padding - ETH_HLEN);
+		if (pskb_trim_rcsum(skb, start_of_padding - ETH_HLEN))
+			return NULL;
 	/* Trap-to-host frame, no timestamp trailer */
 	} else {
 		*source_port = SJA1110_RX_HEADER_SRC_PORT(rx_header);
-- 
2.30.3