From a2af6cb8a699966e13c0bbcafc41da2f0e814b86 Mon Sep 17 00:00:00 2001 From: Adam Jackson Date: Mon, 10 Nov 2014 12:13:43 -0500 Subject: [PATCH 30/31] glx: Length checking for RenderLarge requests (v2) [CVE-2014-8098 3/8] 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) Reviewed-by: Michal Srb Reviewed-by: Andy Ritger Signed-off-by: Adam Jackson Signed-off-by: Alan Coopersmith Signed-off-by: Fedora X Ninjas --- glx/glxcmds.c | 57 ++++++++++++++++++++++++++++++++++----------------------- 1 file changed, 34 insertions(+), 23 deletions(-) diff --git a/glx/glxcmds.c b/glx/glxcmds.c index 969bf01..4715328 100644 --- a/glx/glxcmds.c +++ b/glx/glxcmds.c @@ -2055,6 +2055,8 @@ __glXDisp_RenderLarge(__GLXclientState * cl, GLbyte * pc) __GLX_DECLARE_SWAP_VARIABLES; + REQUEST_AT_LEAST_SIZE(xGLXRenderLargeReq); + req = (xGLXRenderLargeReq *) pc; if (client->swapped) { __GLX_SWAP_SHORT(&req->length); @@ -2070,12 +2072,14 @@ __glXDisp_RenderLarge(__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); @@ -2085,7 +2089,7 @@ __glXDisp_RenderLarge(__GLXclientState * cl, GLbyte * pc) if (cl->largeCmdRequestsSoFar == 0) { __GLXrenderSizeData entry; - int extra; + int extra = 0; size_t cmdlen; int err; @@ -2098,13 +2102,17 @@ __glXDisp_RenderLarge(__GLXclientState * cl, GLbyte * pc) return __glXError(GLXBadLargeRequest); } + if (dataBytes < __GLX_RENDER_LARGE_HDR_SIZE) + return BadLength; + hdr = (__GLXrenderLargeHeader *) pc; if (client->swapped) { __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; /* ** Check for core opcodes and grab entry data. @@ -2126,17 +2134,13 @@ __glXDisp_RenderLarge(__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. */ @@ -2166,6 +2170,7 @@ __glXDisp_RenderLarge(__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. @@ -2184,11 +2189,18 @@ __glXDisp_RenderLarge(__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 __glXError(GLXBadLargeRequest); + } + + if (bytesSoFar > cl->largeCmdBytesTotal) { client->errorValue = dataBytes; __glXResetLargeCommandStatus(cl); return __glXError(GLXBadLargeRequest); } + memcpy(cl->largeCmdBuf + cl->largeCmdBytesSoFar, pc, dataBytes); cl->largeCmdBytesSoFar += dataBytes; cl->largeCmdRequestsSoFar++; @@ -2200,17 +2212,16 @@ __glXDisp_RenderLarge(__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) { client->errorValue = dataBytes; __glXResetLargeCommandStatus(cl); return __glXError(GLXBadLargeRequest); -- 1.9.3