[PATCH net-next v5] sctp: auth: discard auth_chunk when skb_clone fails

[luoqing]

From: Qing Luo <luoqing@xxxxxxxxxx>

When processing AUTH + COOKIE-ECHO packets, if skb_clone() fails
due to memory pressure, chunk->auth_chunk is NULL. The original
code still sets chunk->auth = 1 and continues, leaving the
COOKIE-ECHO to be processed without a valid auth_chunk for
deferred verification.

Discard the AUTH chunk early via pdiscard when skb_clone() fails,
so that the receive loop can continue processing remaining chunks
in the inqueue instead of stalling the entire packet.

Signed-off-by: Qing Luo <luoqing@xxxxxxxxxx>
---
 net/sctp/associola.c   | 4 ++++
 net/sctp/endpointola.c | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index 62d3cc155809..a5f2835dbe0f 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -999,6 +999,10 @@ static void sctp_assoc_bh_rcv(struct work_struct *work)
 			if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
 				chunk->auth_chunk = skb_clone(chunk->skb,
 							      GFP_ATOMIC);
+				if (!chunk->auth_chunk) {
+					chunk->pdiscard = 1;
+					continue;
+				}
 				chunk->auth = 1;
 				continue;
 			}
diff --git a/net/sctp/endpointola.c b/net/sctp/endpointola.c
index dfb1719275db..a15b599b20b7 100644
--- a/net/sctp/endpointola.c
+++ b/net/sctp/endpointola.c
@@ -368,6 +368,10 @@ static void sctp_endpoint_bh_rcv(struct work_struct *work)
 			if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
 				chunk->auth_chunk = skb_clone(chunk->skb,
 								GFP_ATOMIC);
+				if (!chunk->auth_chunk) {
+					chunk->pdiscard = 1;
+					continue;
+				}
 				chunk->auth = 1;
 				continue;
 			}
-- 
2.25.1

Thank you for the review and the suggestion.

I agree that using chunk->pdiscard = 1; continue; is better than break;. It avoids stalling the entire inqueue under memory pressure and follows the existing discard convention in SCTP. I will update the patch accordingly.

Thanks,
luoqing