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Correct bounds checking in XkbSetNames() 

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>
This commit is contained in:
Matthieu Herrb 2020-08-18 14:46:32 +02:00
parent 1cccb486d4
commit f7cd1276bb
1 changed files with 48 additions and 0 deletions
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48
xkb/xkb.c
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@ -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
@ -4048,6 +4061,8 @@ _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) {
@ -4077,6 +4092,8 @@ _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)
@ -4086,6 +4103,8 @@ _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;
@ -4098,6 +4117,9 @@ _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) {
@ -4110,6 +4132,9 @@ _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);
@ -4123,6 +4148,9 @@ _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);
@ -4144,9 +4172,14 @@ _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) {
@ -4154,6 +4187,9 @@ _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;
@ -4347,6 +4383,8 @@ 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) {
@ -4354,6 +4392,8 @@ 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) {
@ -4361,6 +4401,8 @@ 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) {
@ -4368,6 +4410,8 @@ 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) {
@ -4375,6 +4419,8 @@ 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) {
@ -4382,6 +4428,8 @@ 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) {