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From e9fa7c1c88a8130a48f772c92b186b8b777986b5 Mon Sep 17 00:00:00 2001
From: Adam Jackson <ajax@redhat.com>
Date: Fri, 18 Jan 2008 14:41:20 -0500
Subject: [PATCH] CVE-2007-6429: Don't spuriously reject <8bpp shm pixmaps.
Move size validation after depth validation, and only validate size if
the bpp of the pixmap format is > 8. If bpp < 8 then we're already
protected from overflow by the width and height checks.
---
Xext/shm.c | 36 ++++++++++++++++++++----------------
1 files changed, 20 insertions(+), 16 deletions(-)
diff --git a/Xext/shm.c b/Xext/shm.c
index c545e49..e46f6fc 100644
--- a/Xext/shm.c
+++ b/Xext/shm.c
@@ -783,14 +783,6 @@ ProcPanoramiXShmCreatePixmap(
}
if (width > 32767 || height > 32767)
return BadAlloc;
- size = PixmapBytePad(width, depth) * height;
- if (sizeof(size) == 4) {
- if (size < width * height)
- return BadAlloc;
- /* thankfully, offset is unsigned */
- if (stuff->offset + size < size)
- return BadAlloc;
- }
if (stuff->depth != 1)
{
@@ -801,7 +793,17 @@ ProcPanoramiXShmCreatePixmap(
client->errorValue = stuff->depth;
return BadValue;
}
+
CreatePmap:
+ size = PixmapBytePad(width, depth) * height;
+ if (sizeof(size) == 4 && BitsPerPixel(depth) > 8) {
+ if (size < width * height)
+ return BadAlloc;
+ /* thankfully, offset is unsigned */
+ if (stuff->offset + size < size)
+ return BadAlloc;
+ }
+
VERIFY_SHMSIZE(shmdesc, stuff->offset, size, client);
if(!(newPix = (PanoramiXRes *) xalloc(sizeof(PanoramiXRes))))
@@ -1126,14 +1128,6 @@ ProcShmCreatePixmap(client)
}
if (width > 32767 || height > 32767)
return BadAlloc;
- size = PixmapBytePad(width, depth) * height;
- if (sizeof(size) == 4) {
- if (size < width * height)
- return BadAlloc;
- /* thankfully, offset is unsigned */
- if (stuff->offset + size < size)
- return BadAlloc;
- }
if (stuff->depth != 1)
{
@@ -1144,7 +1138,17 @@ ProcShmCreatePixmap(client)
client->errorValue = stuff->depth;
return BadValue;
}
+
CreatePmap:
+ size = PixmapBytePad(width, depth) * height;
+ if (sizeof(size) == 4 && BitsPerPixel(depth) > 8) {
+ if (size < width * height)
+ return BadAlloc;
+ /* thankfully, offset is unsigned */
+ if (stuff->offset + size < size)
+ return BadAlloc;
+ }
+
VERIFY_SHMSIZE(shmdesc, stuff->offset, size, client);
pMap = (*shmFuncs[pDraw->pScreen->myNum]->CreatePixmap)(
pDraw->pScreen, stuff->width,
--
1.5.3.8
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