netdev - [PATCH] net/sctp: fix a null dereference in sctp_disposition sctp_sf_do_5_1D

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Message-ID: <20251002091448.11-1-alsp705@gmail.com>
Date: Thu,  2 Oct 2025 12:14:47 +0300
From: Alexandr Sapozhnkiov <alsp705@...il.com>
To: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
	Xin Long <lucien.xin@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	linux-sctp@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Alexandr Sapozhnikov <alsp705@...il.com>,
	lvc-project@...uxtesting.org
Subject: [PATCH] net/sctp: fix a null dereference in sctp_disposition sctp_sf_do_5_1D_ce()

From: Alexandr Sapozhnikov <alsp705@...il.com>

If new_asoc->peer.adaptation_ind=0 and sctp_ulpevent_make_authkey=0 
and sctp_ulpevent_make_authkey() returns 0, then the variable 
ai_ev remains zero and the zero will be dereferenced 
in the sctp_ulpevent_free() function.

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

Signed-off-by: Alexandr Sapozhnikov <alsp705@...il.com>
---
 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 5adf0c0a6c1a..056544e1ca15 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:
-- 
2.43.0