From 352687dcfcfc35fe3817c9baf1bc891401165605 Mon Sep 17 00:00:00 2001 From: Adam Jackson Date: Mon, 10 Nov 2014 12:13:36 -0500 Subject: [PATCH 18/31] glx: Be more paranoid about variable-length requests [CVE-2014-8093 1/6] If the size computation routine returns -1 we should just reject the request outright. Clamping it to zero could give an attacker the opportunity to also mangle cmdlen in such a way that the subsequent length check passes, and the request would get executed, thus passing data we wanted to reject to the renderer. Reviewed-by: Keith Packard Reviewed-by: 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 | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/glx/glxcmds.c b/glx/glxcmds.c index c1f4e22..5b50785 100644 --- a/glx/glxcmds.c +++ b/glx/glxcmds.c @@ -2008,7 +2008,7 @@ __glXDisp_Render(__GLXclientState * cl, GLbyte * pc) extra = (*entry.varsize) (pc + __GLX_RENDER_HDR_SIZE, client->swapped); if (extra < 0) { - extra = 0; + return BadLength; } if (cmdlen != __GLX_PAD(entry.bytes + extra)) { return BadLength; @@ -2125,7 +2125,7 @@ __glXDisp_RenderLarge(__GLXclientState * cl, GLbyte * pc) extra = (*entry.varsize) (pc + __GLX_RENDER_LARGE_HDR_SIZE, client->swapped); if (extra < 0) { - extra = 0; + return BadLength; } /* large command's header is 4 bytes longer, so add 4 */ if (cmdlen != __GLX_PAD(entry.bytes + 4 + extra)) { -- 1.9.3