[PATCH v2] net: dsa: Check return value from skb_trim_rcsum()

Artem Chernyshev
2022-11-29T19:47:39Z

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