From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Ricardo Leitner Subject: [PATCH net 2/3] sctp: add a ceiling to optlen in some sockopts Date: Mon, 8 Jan 2018 19:02:28 -0200 Message-ID: References: Cc: linux-sctp@vger.kernel.org, Neil Horman , Vlad Yasevich , haliu@redhat.com To: netdev@vger.kernel.org Return-path: Received: from mail-qk0-f194.google.com ([209.85.220.194]:41340 "EHLO mail-qk0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932761AbeAHVEV (ORCPT ); Mon, 8 Jan 2018 16:04:21 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Hangbin Liu reported that some sockopt calls could cause the kernel to log a warning on memory allocation failure if the user supplied a large optlen value. That is because some of them called memdup_user() without a ceiling on optlen, allowing it to try to allocate really large buffers. This patch adds a ceiling by limiting optlen to the maximum allowed that would still make sense for these sockopt. Reported-by: Hangbin Liu Signed-off-by: Marcelo Ricardo Leitner --- net/sctp/socket.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 54c046783a89e76c9909ee85c83e6be38ada41a7..022b94f11fd8ac0d3b839b16dfc14f86abf2324f 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -3498,6 +3498,8 @@ static int sctp_setsockopt_hmac_ident(struct sock *sk, if (optlen < sizeof(struct sctp_hmacalgo)) return -EINVAL; + optlen = min_t(unsigned int, optlen, sizeof(struct sctp_hmacalgo) + + SCTP_AUTH_NUM_HMACS * sizeof(u16)); hmacs = memdup_user(optval, optlen); if (IS_ERR(hmacs)) @@ -3536,6 +3538,11 @@ static int sctp_setsockopt_auth_key(struct sock *sk, if (optlen <= sizeof(struct sctp_authkey)) return -EINVAL; + /* authkey->sca_keylength is u16, so optlen can't be bigger than + * this. + */ + optlen = min_t(unsigned int, optlen, USHRT_MAX + + sizeof(struct sctp_authkey)); authkey = memdup_user(optval, optlen); if (IS_ERR(authkey)) @@ -3893,6 +3900,9 @@ static int sctp_setsockopt_reset_streams(struct sock *sk, if (optlen < sizeof(*params)) return -EINVAL; + /* srs_number_streams is u16, so optlen can't be bigger than this. */ + optlen = min_t(unsigned int, optlen, USHRT_MAX + + sizeof(__u16) * sizeof(*params)); params = memdup_user(optval, optlen); if (IS_ERR(params)) -- 2.14.3