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tigervnc/0005-Handle-empty-Tight-gradient-rects.patch
Stefan Dirsch d26ec6dbd4 - TigerVNC security fix:
0001-Make-ZlibInStream-more-robust-against-failures.patch
  0002-Encapsulate-PixelBuffer-internal-details.patch
  0003-Restrict-PixelBuffer-dimensions-to-safe-values.patch
  0004-Add-write-protection-to-OffsetPixelBuffer.patch
  0005-Handle-empty-Tight-gradient-rects.patch
  0006-Add-unit-test-for-PixelFormat-sanity-checks.patch
  0007-Fix-depth-sanity-test-in-PixelFormat.patch
  0008-Add-sanity-checks-for-PixelFormat-shift-values.patch
  0009-Remove-unused-FixedMemOutStream.patch
  0010-Use-size_t-for-lengths-in-stream-objects.patch
  0011-Be-defensive-about-overflows-in-stream-objects.patch
  0012-Add-unit-tests-for-PixelFormat.is888-detection.patch
  0013-Handle-pixel-formats-with-odd-shift-values.patch
  * stack use-after-return due to incorrect usage of stack memory
    in ZRLEDecoder (CVE-2019-15691, bsc#1159856)
  * improper value checks in CopyRectDecode may lead to heap
    buffer overflow (CVE-2019-15692, bsc#1160250)
  * heap buffer overflow in TightDecoder::FilterGradient
    (CVE-2019-15693, bsc#1159858)
  * improper error handling in processing MemOutStream may lead
    to heap buffer overflow (CVE-2019-15694, bsc#1160251
  * stack buffer overflow, which could be triggered from
    CMsgReader::readSetCurso (CVE-2019-15695, bsc#1159860)

OBS-URL: https://build.opensuse.org/package/show/X11:XOrg/tigervnc?expand=0&rev=168
2020-01-07 16:03:18 +00:00

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2.5 KiB
Diff

From b4ada8d0c6dac98c8b91fc64d112569a8ae5fb95 Mon Sep 17 00:00:00 2001
From: Pierre Ossman <ossman@cendio.se>
Date: Tue, 10 Sep 2019 15:36:42 +0200
Subject: [PATCH] Handle empty Tight gradient rects
We always assumed there would be one pixel per row so a rect with
a zero width would result in us writing to unknown memory.
This could theoretically be used by a malicious server to inject
code in to the viewer process.
Issue found by Pavel Cheremushkin from Kaspersky Lab.
---
common/rfb/tightDecode.h | 37 +++++++++++++++++++++----------------
1 file changed, 21 insertions(+), 16 deletions(-)
diff --git a/common/rfb/tightDecode.h b/common/rfb/tightDecode.h
index b6e86ed5..8f77aebd 100644
--- a/common/rfb/tightDecode.h
+++ b/common/rfb/tightDecode.h
@@ -56,15 +56,17 @@ TightDecoder::FilterGradient24(const rdr::U8 *inbuf,
int rectWidth = r.width();
for (y = 0; y < rectHeight; y++) {
- /* First pixel in a row */
- for (c = 0; c < 3; c++) {
- pix[c] = inbuf[y*rectWidth*3+c] + prevRow[c];
- thisRow[c] = pix[c];
- }
- pf.bufferFromRGB((rdr::U8*)&outbuf[y*stride], pix, 1);
+ for (x = 0; x < rectWidth; x++) {
+ /* First pixel in a row */
+ if (x == 0) {
+ for (c = 0; c < 3; c++) {
+ pix[c] = inbuf[y*rectWidth*3+c] + prevRow[c];
+ thisRow[c] = pix[c];
+ }
+ pf.bufferFromRGB((rdr::U8*)&outbuf[y*stride], pix, 1);
+ continue;
+ }
- /* Remaining pixels of a row */
- for (x = 1; x < rectWidth; x++) {
for (c = 0; c < 3; c++) {
est[c] = prevRow[x*3+c] + pix[c] - prevRow[(x-1)*3+c];
if (est[c] > 0xff) {
@@ -103,17 +105,20 @@ void TightDecoder::FilterGradient(const rdr::U8* inbuf,
int rectWidth = r.width();
for (y = 0; y < rectHeight; y++) {
- /* First pixel in a row */
- pf.rgbFromBuffer(pix, &inbuf[y*rectWidth], 1);
- for (c = 0; c < 3; c++)
- pix[c] += prevRow[c];
+ for (x = 0; x < rectWidth; x++) {
+ /* First pixel in a row */
+ if (x == 0) {
+ pf.rgbFromBuffer(pix, &inbuf[y*rectWidth], 1);
+ for (c = 0; c < 3; c++)
+ pix[c] += prevRow[c];
- memcpy(thisRow, pix, sizeof(pix));
+ memcpy(thisRow, pix, sizeof(pix));
- pf.bufferFromRGB((rdr::U8*)&outbuf[y*stride], pix, 1);
+ pf.bufferFromRGB((rdr::U8*)&outbuf[y*stride], pix, 1);
+
+ continue;
+ }
- /* Remaining pixels of a row */
- for (x = 1; x < rectWidth; x++) {
for (c = 0; c < 3; c++) {
est[c] = prevRow[x*3+c] + pix[c] - prevRow[(x-1)*3+c];
if (est[c] > 255) {
--
2.16.4