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| | Fix CVE-2016-7943:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-7943.
Patch copied from upstream source repository:
https://cgit.freedesktop.org/xorg/lib/libX11/commit/?id=8c29f1607a31dac0911e45a0dd3d74173822b3c9
From 8c29f1607a31dac0911e45a0dd3d74173822b3c9 Mon Sep 17 00:00:00 2001
From: Tobias Stoeckmann <tobias@stoeckmann.org>
Date: Sun, 25 Sep 2016 21:22:57 +0200
Subject: [PATCH] The validation of server responses avoids out of boundary
accesses.
v2: FontNames.c return a NULL list whenever a single
length field from the server is incohent.
Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Reviewed-by: Matthieu Herrb <matthieu@herrb.eu>
---
src/FontNames.c | 23 +++++++++++++++++------
src/ListExt.c | 12 ++++++++----
src/ModMap.c | 3 ++-
3 files changed, 27 insertions(+), 11 deletions(-)
diff --git a/src/FontNames.c b/src/FontNames.c
index 21dcafe..e55f338 100644
--- a/src/FontNames.c
+++ b/src/FontNames.c
@@ -66,7 +66,7 @@ int *actualCount) /* RETURN */
if (rep.nFonts) {
flist = Xmalloc (rep.nFonts * sizeof(char *));
- if (rep.length < (INT_MAX >> 2)) {
+ if (rep.length > 0 && rep.length < (INT_MAX >> 2)) {
rlen = rep.length << 2;
ch = Xmalloc(rlen + 1);
/* +1 to leave room for last null-terminator */
@@ -93,11 +93,22 @@ int *actualCount) /* RETURN */
if (ch + length < chend) {
flist[i] = ch + 1; /* skip over length */
ch += length + 1; /* find next length ... */
- length = *(unsigned char *)ch;
- *ch = '\0'; /* and replace with null-termination */
- count++;
- } else
- flist[i] = NULL;
+ if (ch <= chend) {
+ length = *(unsigned char *)ch;
+ *ch = '\0'; /* and replace with null-termination */
+ count++;
+ } else {
+ Xfree(flist);
+ flist = NULL;
+ count = 0;
+ break;
+ }
+ } else {
+ Xfree(flist);
+ flist = NULL;
+ count = 0;
+ break;
+ }
}
}
*actualCount = count;
diff --git a/src/ListExt.c b/src/ListExt.c
index be6b989..0516e45 100644
--- a/src/ListExt.c
+++ b/src/ListExt.c
@@ -55,7 +55,7 @@ char **XListExtensions(
if (rep.nExtensions) {
list = Xmalloc (rep.nExtensions * sizeof (char *));
- if (rep.length < (INT_MAX >> 2)) {
+ if (rep.length > 0 && rep.length < (INT_MAX >> 2)) {
rlen = rep.length << 2;
ch = Xmalloc (rlen + 1);
/* +1 to leave room for last null-terminator */
@@ -80,9 +80,13 @@ char **XListExtensions(
if (ch + length < chend) {
list[i] = ch+1; /* skip over length */
ch += length + 1; /* find next length ... */
- length = *ch;
- *ch = '\0'; /* and replace with null-termination */
- count++;
+ if (ch <= chend) {
+ length = *ch;
+ *ch = '\0'; /* and replace with null-termination */
+ count++;
+ } else {
+ list[i] = NULL;
+ }
} else
list[i] = NULL;
}
diff --git a/src/ModMap.c b/src/ModMap.c
index a809aa2..49a5d08 100644
--- a/src/ModMap.c
+++ b/src/ModMap.c
@@ -42,7 +42,8 @@ XGetModifierMapping(register Display *dpy)
GetEmptyReq(GetModifierMapping, req);
(void) _XReply (dpy, (xReply *)&rep, 0, xFalse);
- if (rep.length < (INT_MAX >> 2)) {
+ if (rep.length < (INT_MAX >> 2) &&
+ (rep.length >> 1) == rep.numKeyPerModifier) {
nbytes = (unsigned long)rep.length << 2;
res = Xmalloc(sizeof (XModifierKeymap));
if (res)
--
2.10.1
|