gnu: libxtst: Fix CVE-2016-{7951,7952}.

* gnu/packages/patches/libxtst-CVE-2016-7951-CVE-2016-7952.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/xorg.scm (libxtst)[replacement]: New field.
(libxtst/fixed): New variable.

2 files changed, 160 insertions, 0 deletions

diff --git a/gnu/packages/patches/libxtst-CVE-2016-7951-CVE-2016-7952.patch b/gnu/packages/patches/libxtst-CVE-2016-7951-CVE-2016-7952.patch
new file mode 100644
index 0000000000..9df6cf3f4d
--- /dev/null
+++ b/gnu/packages/patches/libxtst-CVE-2016-7951-CVE-2016-7952.patch
@@ -0,0 +1,152 @@
+Fix CVE-2016-7951 and CVE-2016-7952
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-7951
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-7952
+
+Patch copied from upstream source repository:
+
+https://cgit.freedesktop.org/xorg/lib/libXtst/commit/?id=9556ad67af3129ec4a7a4f4b54a0d59701beeae3
+
+From 9556ad67af3129ec4a7a4f4b54a0d59701beeae3 Mon Sep 17 00:00:00 2001
+From: Tobias Stoeckmann <tobias@stoeckmann.org>
+Date: Sun, 25 Sep 2016 21:37:01 +0200
+Subject: [PATCH] Out of boundary access and endless loop in libXtst
+
+A lack of range checks in libXtst allows out of boundary accesses.
+The checks have to be done in-place here, because it cannot be done
+without in-depth knowledge of the read data.
+
+If XRecordStartOfData, XRecordEndOfData, or XRecordClientDied
+without a client sequence have attached data, an endless loop would
+occur. The do-while-loop continues until the current index reaches
+the end. But in these cases, the current index would not be
+incremented, leading to an endless processing.
+
+Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
+Reviewed-by: Matthieu Herrb <matthieu@herrb.eu>
+---
+ src/XRecord.c | 43 +++++++++++++++++++++++++++++++++++++++----
+ 1 file changed, 39 insertions(+), 4 deletions(-)
+
+diff --git a/src/XRecord.c b/src/XRecord.c
+index 50420c0..fefd842 100644
+--- a/src/XRecord.c
++++ b/src/XRecord.c
+@@ -749,15 +749,23 @@ parse_reply_call_callback(
+ 	switch (rep->category) {
+ 	case XRecordFromServer:
+ 	    if (rep->elementHeader&XRecordFromServerTime) {
++		if (current_index + 4 > rep->length << 2)
++		    return Error;
+ 		EXTRACT_CARD32(rep->clientSwapped,
+ 			       reply->buf+current_index,
+ 			       data->server_time);
+ 		current_index += 4;
+ 	    }
++	    if (current_index + 1 > rep->length << 2)
++		return Error;
+ 	    switch (reply->buf[current_index]) {
+ 	    case X_Reply: /* reply */
++		if (current_index + 8 > rep->length << 2)
++		    return Error;
+ 		EXTRACT_CARD32(rep->clientSwapped,
+ 			       reply->buf+current_index+4, datum_bytes);
++		if (datum_bytes < 0 || datum_bytes > ((INT_MAX >> 2) - 8))
++		    return Error;
+ 		datum_bytes = (datum_bytes+8) << 2;
+ 		break;
+ 	    default: /* error or event */
+@@ -766,52 +774,73 @@ parse_reply_call_callback(
+ 	    break;
+ 	case XRecordFromClient:
+ 	    if (rep->elementHeader&XRecordFromClientTime) {
++		if (current_index + 4 > rep->length << 2)
++		    return Error;
+ 		EXTRACT_CARD32(rep->clientSwapped,
+ 			       reply->buf+current_index,
+ 			       data->server_time);
+ 		current_index += 4;
+ 	    }
+ 	    if (rep->elementHeader&XRecordFromClientSequence) {
++		if (current_index + 4 > rep->length << 2)
++		    return Error;
+ 		EXTRACT_CARD32(rep->clientSwapped,
+ 			       reply->buf+current_index,
+ 			       data->client_seq);
+ 		current_index += 4;
+ 	    }
++	    if (current_index + 4 > rep->length<<2)
++		return Error;
+ 	    if (reply->buf[current_index+2] == 0
+ 		&& reply->buf[current_index+3] == 0) /* needn't swap 0 */
+ 	    {	/* BIG-REQUESTS */
++		if (current_index + 8 > rep->length << 2)
++		    return Error;
+ 		EXTRACT_CARD32(rep->clientSwapped,
+ 			       reply->buf+current_index+4, datum_bytes);
+ 	    } else {
+ 		EXTRACT_CARD16(rep->clientSwapped,
+ 			       reply->buf+current_index+2, datum_bytes);
+ 	    }
++	    if (datum_bytes < 0 || datum_bytes > INT_MAX >> 2)
++		return Error;
+ 	    datum_bytes <<= 2;
+ 	    break;
+ 	case XRecordClientStarted:
++	    if (current_index + 8 > rep->length << 2)
++		return Error;
+ 	    EXTRACT_CARD16(rep->clientSwapped,
+ 			   reply->buf+current_index+6, datum_bytes);
+ 	    datum_bytes = (datum_bytes+2) << 2;
+ 	    break;
+ 	case XRecordClientDied:
+ 	    if (rep->elementHeader&XRecordFromClientSequence) {
++		if (current_index + 4 > rep->length << 2)
++		    return Error;
+ 		EXTRACT_CARD32(rep->clientSwapped,
+ 			       reply->buf+current_index,
+ 			       data->client_seq);
+ 		current_index += 4;
+-	    }
+-	    /* fall through */
++	    } else if (current_index < rep->length << 2)
++		return Error;
++	    datum_bytes = 0;
++	    break;
+ 	case XRecordStartOfData:
+ 	case XRecordEndOfData:
++	    if (current_index < rep->length << 2)
++		return Error;
+ 	    datum_bytes = 0;
++	    break;
+ 	}
+ 
+ 	if (datum_bytes > 0) {
+-	    if (current_index + datum_bytes > rep->length << 2)
++	    if (INT_MAX - datum_bytes < (rep->length << 2) - current_index) {
+ 		fprintf(stderr,
+ 			"XRecord: %lu-byte reply claims %d-byte element (seq %lu)\n",
+-			(long)rep->length << 2, current_index + datum_bytes,
++			(unsigned long)rep->length << 2, current_index + datum_bytes,
+ 			dpy->last_request_read);
++		return Error;
++	    }
+ 	    /*
+ 	     * This assignment (and indeed the whole buffer sharing
+ 	     * scheme) assumes arbitrary 4-byte boundaries are
+@@ -863,6 +892,12 @@ XRecordEnableContext(Display *dpy, XRecordContext context,
+ 	    return 0;
+ 	}
+ 
++	if (rep.length > INT_MAX >> 2) {
++	    UnlockDisplay(dpy);
++	    SyncHandle();
++	    return 0;
++	}
++
+ 	if (rep.length > 0) {
+ 	    reply = alloc_reply_buffer(info, rep.length<<2);
+ 	    if (!reply) {
+-- 
+2.10.1
+
diff --git a/gnu/packages/xorg.scm b/gnu/packages/xorg.scm
index 2df6631e2a..111de2b65a 100644
--- a/gnu/packages/xorg.scm
+++ b/gnu/packages/xorg.scm
@@ -4639,6 +4639,7 @@ cannot be adequately worked around on the client side of the wire.")
 (define-public libxtst
   (package
     (name "libxtst")
+    (replacement libxtst/fixed)
     (version "1.2.2")
     (source
       (origin
@@ -4674,6 +4675,13 @@ The RECORD extension supports the recording and reporting of all core X
 protocol and arbitrary X extension protocol.")
     (license license:x11)))
 
+(define libxtst/fixed
+  (package
+    (inherit libxtst)
+    (source (origin
+              (inherit (package-source libxtst))
+              (patches (search-patches
+                         "libxtst-CVE-2016-7951-CVE-2016-7952.patch"))))))
 
 (define-public libxv
   (package