[X2Go-Dev] [X2Go-Commits] [nx-libs] 51/52: glx: Length checking for RenderLarge requests (v2) [CVE-2014-8098 3/8] (v3)
Michael DePaulo
mikedep333 at gmail.com
Mon Feb 16 14:34:28 CET 2015
On Sun, Feb 15, 2015 at 8:23 PM, Mihai Moldovan <ionic at ionic.de> wrote:
> On 14.02.2015 05:47 PM, git-admin at x2go.org wrote:
>> This is an automated email from the git hooks/post-receive script.
>>
>> x2go pushed a commit to branch 3.6.x
>> in repository nx-libs.
>>
>> commit 9c558f9ca2c0d4e34fa71dff272ed1c39c22cd9d
>> Author: Adam Jackson <ajax at redhat.com>
>> Date: Mon Nov 10 12:13:43 2014 -0500
>>
>> glx: Length checking for RenderLarge requests (v2) [CVE-2014-8098 3/8] (v3)
>>
>> This is a half-measure until we start passing request length into the
>> varsize function, but it's better than the nothing we had before.
>>
>> v2: Verify that there's at least a large render header's worth of
>> dataBytes (Julien Cristau)
>>
>> v3: backport to RHEL5
>>
>> v4: backport to nx-libs 3.6.x (Mike DePaulo)
>>
>> Reviewed-by: Michal Srb <msrb at suse.com>
>> Reviewed-by: Andy Ritger <aritger at nvidia.com>
>> Signed-off-by: Adam Jackson <ajax at redhat.com>
>> Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
>> Signed-off-by: Fedora X Ninjas <x at fedoraproject.org>
>> Signed-off-by: Dave Airlie <airlied at redhat.com>
>>
>> fixup swap
>> ---
>> nx-X11/programs/Xserver/GL/glx/glxcmds.c | 58 +++++++++++++++----------
>> nx-X11/programs/Xserver/GL/glx/glxcmdsswap.c | 59 ++++++++++++++++----------
>> 2 files changed, 71 insertions(+), 46 deletions(-)
>>
>> diff --git a/nx-X11/programs/Xserver/GL/glx/glxcmds.c b/nx-X11/programs/Xserver/GL/glx/glxcmds.c
>> index 831c65b..20c12f3 100644
>> --- a/nx-X11/programs/Xserver/GL/glx/glxcmds.c
>> +++ b/nx-X11/programs/Xserver/GL/glx/glxcmds.c
>> @@ -1535,6 +1535,8 @@ int __glXRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> ** duplicated there.
>> */
>>
>> + REQUEST_AT_LEAST_SIZE(xGLXRenderLargeReq);
>> +
>> req = (xGLXRenderLargeReq *) pc;
>> glxc = __glXForceCurrent(cl, req->contextTag, &error);
>> if (!glxc) {
>> @@ -1542,12 +1544,15 @@ int __glXRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> __glXResetLargeCommandStatus(cl);
>> return error;
>> }
>> + if (safe_pad(req->dataBytes) < 0)
>> + return BadLength;
>> +
>> dataBytes = req->dataBytes;
>>
>> /*
>> ** Check the request length.
>> */
>> - if ((req->length << 2) != __GLX_PAD(dataBytes) + sz_xGLXRenderLargeReq) {
>> + if ((req->length << 2) != safe_pad(dataBytes) + sz_xGLXRenderLargeReq) {
>> client->errorValue = req->length;
>> /* Reset in case this isn't 1st request. */
>> __glXResetLargeCommandStatus(cl);
>> @@ -1557,7 +1562,7 @@ int __glXRenderLarge(__GLXclientState *cl, GLbyte *pc)
>>
>> if (cl->largeCmdRequestsSoFar == 0) {
>> __GLXrenderSizeData *entry;
>> - int extra, cmdlen;
>> + int extra = 0, cmdlen;
>> /*
>> ** This is the first request of a multi request command.
>> ** Make enough space in the buffer, then copy the entire request.
>> @@ -1567,9 +1572,13 @@ int __glXRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> return __glXBadLargeRequest;
>> }
>>
>> + if (dataBytes < __GLX_RENDER_LARGE_HDR_SIZE)
>> + return BadLength;
>> +
>> hdr = (__GLXrenderLargeHeader *) pc;
>> - cmdlen = hdr->length;
>> opcode = hdr->opcode;
>> + if ((cmdlen = safe_pad(hdr->length)) < 0)
>> + return BadLength;
>>
>> /*
>> ** Check for core opcodes and grab entry data.
>> @@ -1603,16 +1612,13 @@ int __glXRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> if (extra < 0) {
>> return BadLength;
>> }
>> - /* large command's header is 4 bytes longer, so add 4 */
>> - if (cmdlen != __GLX_PAD(entry->bytes + 4 + extra)) {
>> - return BadLength;
>> - }
>> - } else {
>> - /* constant size command */
>> - if (cmdlen != __GLX_PAD(entry->bytes + 4)) {
>> - return BadLength;
>> - }
>> }
>> +
>> + /* the +4 is safe because we know entry.bytes is small */
>> + if (cmdlen != safe_pad(safe_add(entry->bytes + 4, extra))) {
>> + return BadLength;
>> + }
>> +
>> /*
>> ** Make enough space in the buffer, then copy the entire request.
>> */
>> @@ -1641,6 +1647,7 @@ int __glXRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> ** We are receiving subsequent (i.e. not the first) requests of a
>> ** multi request command.
>> */
>> + int bytesSoFar; /* including this packet */
>>
>> /*
>> ** Check the request number and the total request count.
>> @@ -1659,7 +1666,13 @@ int __glXRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> /*
>> ** Check that we didn't get too much data.
>> */
>> - if ((cl->largeCmdBytesSoFar + dataBytes) > cl->largeCmdBytesTotal) {
>> + if ((bytesSoFar = safe_add(cl->largeCmdBytesSoFar, dataBytes)) < 0) {
>> + client->errorValue = dataBytes;
>> + __glXResetLargeCommandStatus(cl);
>> + return __glXBadLargeRequest;
>> + }
>> +
>> + if (bytesSoFar > cl->largeCmdBytesTotal) {
>> client->errorValue = dataBytes;
>> __glXResetLargeCommandStatus(cl);
>> return __glXBadLargeRequest;
>> @@ -1673,17 +1686,16 @@ int __glXRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> ** This is the last request; it must have enough bytes to complete
>> ** the command.
>> */
>> - /* NOTE: the two pad macros have been added below; they are needed
>> - ** because the client library pads the total byte count, but not
>> - ** the per-request byte counts. The Protocol Encoding says the
>> - ** total byte count should not be padded, so a proposal will be
>> - ** made to the ARB to relax the padding constraint on the total
>> - ** byte count, thus preserving backward compatibility. Meanwhile,
>> - ** the padding done below fixes a bug that did not allow
>> - ** large commands of odd sizes to be accepted by the server.
>> + /* NOTE: the pad macro below is needed because the client library
>> + ** pads the total byte count, but not the per-request byte counts.
>> + ** The Protocol Encoding says the total byte count should not be
>> + ** padded, so a proposal will be made to the ARB to relax the
>> + ** padding constraint on the total byte count, thus preserving
>> + ** backward compatibility. Meanwhile, the padding done below
>> + ** fixes a bug that did not allow large commands of odd sizes to
>> + ** be accepted by the server.
>> */
>> - if (__GLX_PAD(cl->largeCmdBytesSoFar) !=
>> - __GLX_PAD(cl->largeCmdBytesTotal)) {
>> + if (safe_pad(cl->largeCmdBytesSoFar) != cl->largeCmdBytesTotal) {
>
> cl->largeCmdBytesTotal is not wrapped in safe_pad(). This looks odd and could be a mistake.
>
>
>> client->errorValue = dataBytes;
>> __glXResetLargeCommandStatus(cl);
>> return __glXBadLargeRequest;
>> diff --git a/nx-X11/programs/Xserver/GL/glx/glxcmdsswap.c b/nx-X11/programs/Xserver/GL/glx/glxcmdsswap.c
>> index 2685355..2e228c0 100644
>> --- a/nx-X11/programs/Xserver/GL/glx/glxcmdsswap.c
>> +++ b/nx-X11/programs/Xserver/GL/glx/glxcmdsswap.c
>> @@ -587,6 +587,8 @@ int __glXSwapRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> ** duplicated there.
>> */
>>
>> + REQUEST_AT_LEAST_SIZE(xGLXRenderLargeReq);
>> +
>> req = (xGLXRenderLargeReq *) pc;
>> __GLX_SWAP_SHORT(&req->length);
>> __GLX_SWAP_INT(&req->contextTag);
>> @@ -599,12 +601,15 @@ int __glXSwapRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> __glXResetLargeCommandStatus(cl);
>> return error;
>> }
>> + if (safe_pad(req->dataBytes) < 0)
>> + return BadLength;
>> +
>> dataBytes = req->dataBytes;
>>
>> /*
>> ** Check the request length.
>> */
>> - if ((req->length << 2) != __GLX_PAD(dataBytes) + sz_xGLXRenderLargeReq) {
>> + if ((req->length << 2) != safe_pad(dataBytes) + sz_xGLXRenderLargeReq) {
>> client->errorValue = req->length;
>> /* Reset in case this isn't 1st request. */
>> __glXResetLargeCommandStatus(cl);
>> @@ -614,7 +619,7 @@ int __glXSwapRenderLarge(__GLXclientState *cl, GLbyte *pc)
>>
>> if (cl->largeCmdRequestsSoFar == 0) {
>> __GLXrenderSizeData *entry;
>> - int extra;
>> + int extra = 0;
>> size_t cmdlen;
>> /*
>> ** This is the first request of a multi request command.
>> @@ -624,12 +629,17 @@ int __glXSwapRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> client->errorValue = req->requestNumber;
>> return __glXBadLargeRequest;
>> }
>> + if (dataBytes < __GLX_RENDER_LARGE_HDR_SIZE)
>> + return BadLength;
>> +
>> hdr = (__GLXrenderLargeHeader *) pc;
>> __GLX_SWAP_INT(&hdr->length);
>> __GLX_SWAP_INT(&hdr->opcode);
>> - cmdlen = hdr->length;
>> opcode = hdr->opcode;
>>
>> + if ((cmdlen = safe_pad(hdr->length)) < 0)
>> + return BadLength;
>> +
>> if ( (opcode >= __GLX_MIN_RENDER_OPCODE) &&
>> (opcode <= __GLX_MAX_RENDER_OPCODE) ) {
>> entry = &__glXRenderSizeTable[opcode];
>> @@ -661,16 +671,12 @@ int __glXSwapRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> if (extra < 0) {
>> return BadLength;
>> }
>> - /* large command's header is 4 bytes longer, so add 4 */
>> - if (cmdlen != __GLX_PAD(entry->bytes + 4 + extra)) {
>> - return BadLength;
>> - }
>> - } else {
>> - /* constant size command */
>> - if (cmdlen != __GLX_PAD(entry->bytes + 4)) {
>> - return BadLength;
>> - }
>> }
>> + /* the +4 is safe because we know entry->bytes is small */
>> + if (cmdlen != safe_pad(safe_add(entry->bytes + 4, extra))) {
>> + return BadLength;
>> + }
>> +
>> /*
>> ** Make enough space in the buffer, then copy the entire request.
>> */
>> @@ -698,6 +704,7 @@ int __glXSwapRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> ** We are receiving subsequent (i.e. not the first) requests of a
>> ** multi request command.
>> */
>> + int bytesSoFar; /* including this packet */
>>
>> /*
>> ** Check the request number and the total request count.
>> @@ -716,7 +723,13 @@ int __glXSwapRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> /*
>> ** Check that we didn't get too much data.
>> */
>> - if ((cl->largeCmdBytesSoFar + dataBytes) > cl->largeCmdBytesTotal) {
>> + if ((bytesSoFar = safe_add(cl->largeCmdBytesSoFar, dataBytes)) < 0) {
>> + client->errorValue = dataBytes;
>> + __glXResetLargeCommandStatus(cl);
>> + return __glXBadLargeRequest;
>> + }
>> +
>> + if (bytesSoFar > cl->largeCmdBytesTotal) {
>> client->errorValue = dataBytes;
>> __glXResetLargeCommandStatus(cl);
>> return __glXBadLargeRequest;
>> @@ -730,17 +743,17 @@ int __glXSwapRenderLarge(__GLXclientState *cl, GLbyte *pc)
>> ** This is the last request; it must have enough bytes to complete
>> ** the command.
>> */
>> - /* NOTE: the two pad macros have been added below; they are needed
>> - ** because the client library pads the total byte count, but not
>> - ** the per-request byte counts. The Protocol Encoding says the
>> - ** total byte count should not be padded, so a proposal will be
>> - ** made to the ARB to relax the padding constraint on the total
>> - ** byte count, thus preserving backward compatibility. Meanwhile,
>> - ** the padding done below fixes a bug that did not allow
>> - ** large commands of odd sizes to be accepted by the server.
>> + /* NOTE: the pad macro below is needed because the client library
>> + ** pads the total byte count, but not the per-request byte counts.
>> + ** The Protocol Encoding says the total byte count should not be
>> + ** padded, so a proposal will be made to the ARB to relax the
>> + ** padding constraint on the total byte count, thus preserving
>> + ** backward compatibility. Meanwhile, the padding done below
>> + ** fixes a bug that did not allow large commands of odd sizes to
>> + ** be accepted by the server.
>> */
>> - if (__GLX_PAD(cl->largeCmdBytesSoFar) !=
>> - __GLX_PAD(cl->largeCmdBytesTotal)) {
>> +
>> + if (safe_pad(cl->largeCmdBytesSoFar) != cl->largeCmdBytesTotal) {
>
> Similarly not wrapped in safe_pad() here. Not sure whether this happened
> on purpose or is an error.
I will look into this later today, or tomorrow. In the meantime, feel
free to use your judgment. (And feel free to contact upstream.)
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