From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 91D4442DFEC; Tue, 21 Jul 2026 21:42:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784670181; cv=none; b=PJN218odBuqSKgdSkq2PywOb53pzys+Wnfk5kPCEWUwa7Ltq8//FRalWoUMFACcYn5HVxMHot0C1In6wvUSThC4FSHNngcGzQDC3gMReVYhx1oQm7vYGmNMR81B6AHKCNWkmErIhnvi5LJXi0jv34ge7ia/uNvz8948HSYFHqtU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784670181; c=relaxed/simple; bh=o7zRia3RmPBq1uMUgF5hhzUluHo2CT6CYbG/Rcy+3fQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jDeZVHtP4UUHJmAxFMoUIMHrW1tCCwm56ybjJhvrm+6+WX9hLW8Wz7wyq/wh/UwEi4tKt9dl1Bp1lBfwINS5jVobG7jIxAgg4TwVZSSMWqx2aVc408vmjVc+Z74eQOuEZc68ji0ftwVUtQg3Xzi+T1j9ampbFJ9Q85wIDmU01UU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ElmO3ELG; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ElmO3ELG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0350C1F000E9; Tue, 21 Jul 2026 21:42:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784670179; bh=R6RLivcVAPqbEouPlUkcIzKe1I6f3lW+lonCPOav0M4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ElmO3ELGsl/tgnu/2aGv5r2+pG9/Y00Z5SMdVs5NIy6JQ8Oup4hHAM+tfkHGWqXzG KAAFkYlzpd2BUUCYKroOJJoavKYB1dcdi7oiF6DCoLz9Ar3C261notZdX7QRuZfcYC uA/gnfD7Ji7qHj5m7m+nAlyNB9EDvYkeyItV910g= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xiang Mei , Weiming Shi , Xin Long , Paolo Abeni Subject: [PATCH 6.1 0833/1067] sctp: validate STALE_COOKIE cause length before reading staleness Date: Tue, 21 Jul 2026 17:23:54 +0200 Message-ID: <20260721152443.185120509@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152424.521567757@linuxfoundation.org> References: <20260721152424.521567757@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Weiming Shi commit 1cd23ca80784223fa2204e16203f754da4e821f8 upstream. When an ERROR chunk with a STALE_COOKIE cause is received in the COOKIE_ECHOED state, sctp_sf_do_5_2_6_stale() reads the 4-byte Measure of Staleness that follows the cause header: err = (struct sctp_errhdr *)(chunk->skb->data); stale = ntohl(*(__be32 *)((u8 *)err + sizeof(*err))); err is the first cause in the chunk, not the STALE_COOKIE cause that caused the dispatch, and nothing guarantees the staleness field is present. sctp_walk_errors() only requires a cause to be as long as the 4-byte header, so for a STALE_COOKIE cause of length 4 the read runs past the cause, and for a minimal ERROR chunk past skb->tail. The value is echoed to the peer in the Cookie Preservative of the reply INIT, leaking uninitialized memory. sctp_sf_cookie_echoed_err() already walks to the STALE_COOKIE cause, so check its length there and pass it to sctp_sf_do_5_2_6_stale(), which reads that cause instead of the first one. A STALE_COOKIE cause too short to hold the staleness field is discarded. The read is reachable by any peer that can drive an association into COOKIE_ECHOED, including an unprivileged process using a raw SCTP socket in a user and network namespace. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Xiang Mei Assisted-by: Claude:claude-opus-4-8 Cc: stable@vger.kernel.org Signed-off-by: Weiming Shi Acked-by: Xin Long Link: https://patch.msgid.link/20260704033545.2438373-2-bestswngs@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman --- net/sctp/sm_statefuns.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -73,7 +73,8 @@ static enum sctp_disposition sctp_sf_do_ const struct sctp_association *asoc, const union sctp_subtype type, void *arg, - struct sctp_cmd_seq *commands); + struct sctp_cmd_seq *commands, + struct sctp_errhdr *err); static enum sctp_disposition sctp_sf_shut_8_4_5( struct net *net, const struct sctp_endpoint *ep, @@ -2495,9 +2496,15 @@ enum sctp_disposition sctp_sf_cookie_ech * errors. */ sctp_walk_errors(err, chunk->chunk_hdr) { - if (SCTP_ERROR_STALE_COOKIE == err->cause) - return sctp_sf_do_5_2_6_stale(net, ep, asoc, type, - arg, commands); + if (err->cause != SCTP_ERROR_STALE_COOKIE) + continue; + /* The staleness is only meaningful if the cause is long + * enough to hold it; a shorter one is malformed. + */ + if (ntohs(err->length) < sizeof(*err) + sizeof(__be32)) + break; + return sctp_sf_do_5_2_6_stale(net, ep, asoc, type, + arg, commands, err); } /* It is possible to have malformed error causes, and that @@ -2539,13 +2546,13 @@ static enum sctp_disposition sctp_sf_do_ const struct sctp_association *asoc, const union sctp_subtype type, void *arg, - struct sctp_cmd_seq *commands) + struct sctp_cmd_seq *commands, + struct sctp_errhdr *err) { int attempts = asoc->init_err_counter + 1; - struct sctp_chunk *chunk = arg, *reply; struct sctp_cookie_preserve_param bht; struct sctp_bind_addr *bp; - struct sctp_errhdr *err; + struct sctp_chunk *reply; u32 stale; if (attempts > asoc->max_init_attempts) { @@ -2556,8 +2563,6 @@ static enum sctp_disposition sctp_sf_do_ return SCTP_DISPOSITION_DELETE_TCB; } - err = (struct sctp_errhdr *)(chunk->skb->data); - /* When calculating the time extension, an implementation * SHOULD use the RTT information measured based on the * previous COOKIE ECHO / ERROR exchange, and should add no