From: Stefan Wiehler <stefan.wiehler@nokia.com>
Date: Tue, 28 Oct 2025 16:12:27 +0000 (+0100)
Subject: sctp: Prevent TOCTOU out-of-bounds write
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=95aef86ab231f047bb8085c70666059b58f53c09;p=thirdparty%2Flinux.git

sctp: Prevent TOCTOU out-of-bounds write

For the following path not holding the sock lock,

  sctp_diag_dump() -> sctp_for_each_endpoint() -> sctp_ep_dump()

make sure not to exceed bounds in case the address list has grown
between buffer allocation (time-of-check) and write (time-of-use).

Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file")
Signed-off-by: Stefan Wiehler <stefan.wiehler@nokia.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20251028161506.3294376-3-stefan.wiehler@nokia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/sctp/diag.c b/net/sctp/diag.c
index 1a8761f87bf1..5d64dd99ca9a 100644
--- a/net/sctp/diag.c
+++ b/net/sctp/diag.c
@@ -88,6 +88,9 @@ static int inet_diag_msg_sctpladdrs_fill(struct sk_buff *skb,
 		memcpy(info, &laddr->a, sizeof(laddr->a));
 		memset(info + sizeof(laddr->a), 0, addrlen - sizeof(laddr->a));
 		info += addrlen;
+
+		if (!--addrcnt)
+			break;
 	}
 	rcu_read_unlock();