From 1d3a1092c30af660b1366fcd344af745590aa29f Mon Sep 17 00:00:00 2001
From: Matthieu Herrb <matthieu@herrb.eu>
Date: Tue, 18 Aug 2020 14:46:32 +0200
Subject: [PATCH xserver] Correct bounds checking in XkbSetNames()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
CVE-2020-14345 / ZDI 11428
This vulnerability was discovered by:
Jan-Niklas Sohn working with Trend Micro Zero Day Initiative
Signed-off-by: Matthieu Herrb <matthieu@herrb.eu>
(cherry picked from commit 11f22a3bf694d7061d552c99898d843bcdaf0cf1)
Signed-off-by: Michel Dänzer <mdaenzer@redhat.com>
---
xkb/xkb.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/xkb/xkb.c b/xkb/xkb.c
index 3162574a4..2139da7ee 100644
--- a/xkb/xkb.c
+++ b/xkb/xkb.c
@@ -152,6 +152,19 @@ static RESTYPE RT_XKBCLIENT;
#define CHK_REQ_KEY_RANGE(err,first,num,r) \
CHK_REQ_KEY_RANGE2(err,first,num,r,client->errorValue,BadValue)
+static Bool
+_XkbCheckRequestBounds(ClientPtr client, void *stuff, void *from, void *to) {
+ char *cstuff = (char *)stuff;
+ char *cfrom = (char *)from;
+ char *cto = (char *)to;
+
+ return cfrom < cto &&
+ cfrom >= cstuff &&
+ cfrom < cstuff + ((size_t)client->req_len << 2) &&
+ cto >= cstuff &&
+ cto <= cstuff + ((size_t)client->req_len << 2);
+}
+
/***====================================================================***/
int
@@ -4045,6 +4058,8 @@ _XkbSetNamesCheck(ClientPtr client, DeviceIntPtr dev,
client->errorValue = _XkbErrCode2(0x04, stuff->firstType);
return BadAccess;
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp, tmp + stuff->nTypes))
+ return BadLength;
old = tmp;
tmp = _XkbCheckAtoms(tmp, stuff->nTypes, client->swapped, &bad);
if (!tmp) {
@@ -4074,6 +4089,8 @@ _XkbSetNamesCheck(ClientPtr client, DeviceIntPtr dev,
}
width = (CARD8 *) tmp;
tmp = (CARD32 *) (((char *) tmp) + XkbPaddedSize(stuff->nKTLevels));
+ if (!_XkbCheckRequestBounds(client, stuff, width, tmp))
+ return BadLength;
type = &xkb->map->types[stuff->firstKTLevel];
for (i = 0; i < stuff->nKTLevels; i++, type++) {
if (width[i] == 0)
@@ -4083,6 +4100,8 @@ _XkbSetNamesCheck(ClientPtr client, DeviceIntPtr dev,
type->num_levels, width[i]);
return BadMatch;
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp, tmp + width[i]))
+ return BadLength;
tmp = _XkbCheckAtoms(tmp, width[i], client->swapped, &bad);
if (!tmp) {
client->errorValue = bad;
@@ -4095,6 +4114,9 @@ _XkbSetNamesCheck(ClientPtr client, DeviceIntPtr dev,
client->errorValue = 0x08;
return BadMatch;
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp,
+ tmp + Ones(stuff->indicators)))
+ return BadLength;
tmp = _XkbCheckMaskedAtoms(tmp, XkbNumIndicators, stuff->indicators,
client->swapped, &bad);
if (!tmp) {
@@ -4107,6 +4129,9 @@ _XkbSetNamesCheck(ClientPtr client, DeviceIntPtr dev,
client->errorValue = 0x09;
return BadMatch;
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp,
+ tmp + Ones(stuff->virtualMods)))
+ return BadLength;
tmp = _XkbCheckMaskedAtoms(tmp, XkbNumVirtualMods,
(CARD32) stuff->virtualMods,
client->swapped, &bad);
@@ -4120,6 +4145,9 @@ _XkbSetNamesCheck(ClientPtr client, DeviceIntPtr dev,
client->errorValue = 0x0a;
return BadMatch;
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp,
+ tmp + Ones(stuff->groupNames)))
+ return BadLength;
tmp = _XkbCheckMaskedAtoms(tmp, XkbNumKbdGroups,
(CARD32) stuff->groupNames,
client->swapped, &bad);
@@ -4141,9 +4169,14 @@ _XkbSetNamesCheck(ClientPtr client, DeviceIntPtr dev,
stuff->nKeys);
return BadValue;
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp, tmp + stuff->nKeys))
+ return BadLength;
tmp += stuff->nKeys;
}
if ((stuff->which & XkbKeyAliasesMask) && (stuff->nKeyAliases > 0)) {
+ if (!_XkbCheckRequestBounds(client, stuff, tmp,
+ tmp + (stuff->nKeyAliases * 2)))
+ return BadLength;
tmp += stuff->nKeyAliases * 2;
}
if (stuff->which & XkbRGNamesMask) {
@@ -4151,6 +4184,9 @@ _XkbSetNamesCheck(ClientPtr client, DeviceIntPtr dev,
client->errorValue = _XkbErrCode2(0x0d, stuff->nRadioGroups);
return BadValue;
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp,
+ tmp + stuff->nRadioGroups))
+ return BadLength;
tmp = _XkbCheckAtoms(tmp, stuff->nRadioGroups, client->swapped, &bad);
if (!tmp) {
client->errorValue = bad;
@@ -4344,6 +4380,8 @@ ProcXkbSetNames(ClientPtr client)
/* check device-independent stuff */
tmp = (CARD32 *) &stuff[1];
+ if (!_XkbCheckRequestBounds(client, stuff, tmp, tmp + 1))
+ return BadLength;
if (stuff->which & XkbKeycodesNameMask) {
tmp = _XkbCheckAtoms(tmp, 1, client->swapped, &bad);
if (!tmp) {
@@ -4351,6 +4389,8 @@ ProcXkbSetNames(ClientPtr client)
return BadAtom;
}
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp, tmp + 1))
+ return BadLength;
if (stuff->which & XkbGeometryNameMask) {
tmp = _XkbCheckAtoms(tmp, 1, client->swapped, &bad);
if (!tmp) {
@@ -4358,6 +4398,8 @@ ProcXkbSetNames(ClientPtr client)
return BadAtom;
}
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp, tmp + 1))
+ return BadLength;
if (stuff->which & XkbSymbolsNameMask) {
tmp = _XkbCheckAtoms(tmp, 1, client->swapped, &bad);
if (!tmp) {
@@ -4365,6 +4407,8 @@ ProcXkbSetNames(ClientPtr client)
return BadAtom;
}
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp, tmp + 1))
+ return BadLength;
if (stuff->which & XkbPhysSymbolsNameMask) {
tmp = _XkbCheckAtoms(tmp, 1, client->swapped, &bad);
if (!tmp) {
@@ -4372,6 +4416,8 @@ ProcXkbSetNames(ClientPtr client)
return BadAtom;
}
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp, tmp + 1))
+ return BadLength;
if (stuff->which & XkbTypesNameMask) {
tmp = _XkbCheckAtoms(tmp, 1, client->swapped, &bad);
if (!tmp) {
@@ -4379,6 +4425,8 @@ ProcXkbSetNames(ClientPtr client)
return BadAtom;
}
}
+ if (!_XkbCheckRequestBounds(client, stuff, tmp, tmp + 1))
+ return BadLength;
if (stuff->which & XkbCompatNameMask) {
tmp = _XkbCheckAtoms(tmp, 1, client->swapped, &bad);
if (!tmp) {
--
2.28.0