Patch "cifs: dynamic allocation of ntlmssp blob" has been added to the 4.4-stable tree

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

cifs: dynamic allocation of ntlmssp blob

to the 4.4-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:
cifs-dynamic-allocation-of-ntlmssp-blob.patch
and it can be found in the queue-4.4 subdirectory.

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

From: Jerome Marchand <[email protected]>
Date: Thu, 26 May 2016 11:52:25 +0200
Subject: cifs: dynamic allocation of ntlmssp blob

From: Jerome Marchand <[email protected]>

commit b8da344b74c822e966c6d19d6b2321efe82c5d97 upstream.

In sess_auth_rawntlmssp_authenticate(), the ntlmssp blob is allocated statically and its size is an "empirical" 5*sizeof(struct _AUTHENTICATE_MESSAGE) (320B on x86_64). I don't know where this value comes from or if it was ever appropriate, but it is currently
insufficient: the user and domain name in UTF16 could take 1kB by themselves. Because of that, build_ntlmssp_auth_blob() might corrupt memory (out-of-bounds write). The size of ntlmssp_blob in SMB2_sess_setup() is too small too (sizeof(struct _NEGOTIATE_MESSAGE)
+ 500).

This patch allocates the blob dynamically in
build_ntlmssp_auth_blob().

---
 fs/cifs/ntlmssp.h |    2 -
 fs/cifs/sess.c    |   76 +++++++++++++++++++++++++++++-------------------------
 fs/cifs/smb2pdu.c |   10 +------
 3 files changed, 45 insertions(+), 43 deletions(-)

@@ -133,6 +133,6 @@ typedef struct _AUTHENTICATE_MESSAGE {
 
 int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len, struct cifs_ses *ses);
 void build_ntlmssp_negotiate_blob(unsigned char *pbuffer, struct cifs_ses *ses);
-int build_ntlmssp_auth_blob(unsigned char *pbuffer, u16 *buflen,
+int build_ntlmssp_auth_blob(unsigned char **pbuffer, u16 *buflen,
 			struct cifs_ses *ses,
 			const struct nls_table *nls_cp);

@@ -591,7 +591,7 @@ SMB2_sess_setup(const unsigned int xid,
 	u16 blob_length = 0;
 	struct key *spnego_key = NULL;
 	char *security_blob = NULL;
-	char *ntlmssp_blob = NULL;
+	unsigned char *ntlmssp_blob = NULL;
 	bool use_spnego = false; /* else use raw ntlmssp */
 
 	cifs_dbg(FYI, "Session Setup\n");

@@ -716,13 +716,7 @@ ssetup_ntlmssp_authenticate:
 		iov[1].iov_len = blob_length;
 	} else if (phase == NtLmAuthenticate) {
 		req->hdr.SessionId = ses->Suid;
-		ntlmssp_blob = kzalloc(sizeof(struct _NEGOTIATE_MESSAGE) + 500,
-				       GFP_KERNEL);
-		if (ntlmssp_blob == NULL) {
-			rc = -ENOMEM;
-			goto ssetup_exit;
-		}
-		rc = build_ntlmssp_auth_blob(ntlmssp_blob, &blob_length, ses,
+		rc = build_ntlmssp_auth_blob(&ntlmssp_blob, &blob_length, ses,
 					     nls_cp);
 		if (rc) {
 			cifs_dbg(FYI, "build_ntlmssp_auth_blob failed %d\n",

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

queue-4.4/cifs-dynamic-allocation-of-ntlmssp-blob.patch