linux-kernel - [PATCH] sctp: fix null deref in sctp_sf_do_5_1D

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Message-ID: <20250922161557.2716-2-a.simakov@securitycode.ru>
Date: Mon, 22 Sep 2025 19:15:55 +0300
From: Alexey Simakov <a.simakov@...uritycode.ru>
To: <marcelo.leitner@...il.com>
CC: Alexey Simakov <a.simakov@...uritycode.ru>, <lucien.xin@...il.com>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <horms@...nel.org>, <linux-sctp@...r.kernel.org>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<lvc-project@...uxtesting.org>
Subject: [PATCH] sctp: fix null deref in sctp_sf_do_5_1D_ce()

The check of new_asoc->peer.adaptation_ind can fail,
leaving ai_ev uninitialized. In that case, the code
can jump to the nomem_authdev label and later call
sctp_ulpevent_free() with a null ai_ev pointer.
Leading to a potential null dereference.

Add check of ai_ev pointer before call of
sctp_ulpevent_free function.

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

Fixes: 30f6ebf65bc4 ("sctp: add SCTP_AUTH_NO_AUTH type for AUTHENTICATION_EVENT")
Signed-off-by: Alexey Simakov <a.simakov@...uritycode.ru>
---
 net/sctp/sm_statefuns.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index a0524ba8d787..93cac73472c7 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -885,7 +885,8 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,
 	return SCTP_DISPOSITION_CONSUME;
 
 nomem_authev:
-	sctp_ulpevent_free(ai_ev);
+	if (ai_ev)
+		sctp_ulpevent_free(ai_ev);
 nomem_aiev:
 	sctp_ulpevent_free(ev);
 nomem_ev:
-- 
2.34.1