Patch "sctp: add a ceiling to optlen in some sockopts" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

sctp: add a ceiling to optlen in some sockopts

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
sctp-add-a-ceiling-to-optlen-in-some-sockopts.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Marcelo Ricardo Leitner <[email protected]>
Date: Mon, 8 Jan 2018 19:02:28 -0200
Subject: sctp: add a ceiling to optlen in some sockopts

From: Marcelo Ricardo Leitner <[email protected]>

[ Upstream commit 5960cefab9df76600a1a7d4ff592c59e14616e88 ]

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.

---
 net/sctp/socket.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

@@ -3494,6 +3494,8 @@ static int sctp_setsockopt_hmac_ident(st
 
 	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))

@@ -3532,6 +3534,11 @@ static int sctp_setsockopt_auth_key(stru
 
 	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))

@@ -3889,6 +3896,9 @@ static int sctp_setsockopt_reset_streams
 
 	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))

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/sctp-make-use-of-pre-calculated-len.patch queue-4.14/sctp-add-a-ceiling-to-optlen-in-some-sockopts.patch queue-4.14/sctp-fix-the-issue-that-a-__u16-variable-may-overflow-in-sctp_ulpq_renege.patch