sctp: avoid NULL dereference when chunk data buffer is missing
chunk->skb pointer is dereferenced in the if-block where it's supposed
to be NULL only.
chunk->skb can only be NULL if chunk->head_skb is not. Check for frag_list
instead and do it just before replacing chunk->skb. We're sure that
otherwise chunk->skb is non-NULL because of outer if() condition.
Fixes: 90017accff61 ("sctp: Add GSO support")
Signed-off-by: Alexey Simakov <bigalex934@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Link: https://patch.msgid.link/20251021130034.6333-1-bigalex934@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/net/sctp/inqueue.c b/net/sctp/inqueue.c
index 5c16521..f5a7d5a 100644
--- a/net/sctp/inqueue.c
+++ b/net/sctp/inqueue.c
@@ -169,13 +169,14 @@ struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
chunk->head_skb = chunk->skb;
/* skbs with "cover letter" */
- if (chunk->head_skb && chunk->skb->data_len == chunk->skb->len)
+ if (chunk->head_skb && chunk->skb->data_len == chunk->skb->len) {
+ if (WARN_ON(!skb_shinfo(chunk->skb)->frag_list)) {
+ __SCTP_INC_STATS(dev_net(chunk->skb->dev),
+ SCTP_MIB_IN_PKT_DISCARDS);
+ sctp_chunk_free(chunk);
+ goto next_chunk;
+ }
chunk->skb = skb_shinfo(chunk->skb)->frag_list;
-
- if (WARN_ON(!chunk->skb)) {
- __SCTP_INC_STATS(dev_net(chunk->skb->dev), SCTP_MIB_IN_PKT_DISCARDS);
- sctp_chunk_free(chunk);
- goto next_chunk;
}
}
