tigervnc/0008-Add-sanity-checks-for-PixelFormat-shift-values.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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Diff

From cd1d650c532a46e95a1229dffaf281c76a50cdfe Mon Sep 17 00:00:00 2001
From: Pierre Ossman <ossman@cendio.se>
Date: Tue, 10 Sep 2019 16:07:50 +0200
Subject: [PATCH] Add sanity checks for PixelFormat shift values
Otherwise we might be tricked in to reading and writing things at
incorrect offsets for pixels which ultimately could result in an
attacker writing things to the stack or heap and executing things
they shouldn't.
This only affects the server as the client never uses the pixel
format suggested by th server.
Issue found by Pavel Cheremushkin from Kaspersky Lab.
---
common/rfb/PixelFormat.cxx | 7 +++++++
tests/unit/pixelformat.cxx | 6 ++++++
2 files changed, 13 insertions(+)
diff --git a/common/rfb/PixelFormat.cxx b/common/rfb/PixelFormat.cxx
index 2d8142d1..789c43ed 100644
--- a/common/rfb/PixelFormat.cxx
+++ b/common/rfb/PixelFormat.cxx
@@ -682,6 +682,13 @@ bool PixelFormat::isSane(void)
if (totalBits > depth)
return false;
+ if ((bits(redMax) + redShift) > bpp)
+ return false;
+ if ((bits(greenMax) + greenShift) > bpp)
+ return false;
+ if ((bits(blueMax) + blueShift) > bpp)
+ return false;
+
if (((redMax << redShift) & (greenMax << greenShift)) != 0)
return false;
if (((redMax << redShift) & (blueMax << blueShift)) != 0)
diff --git a/tests/unit/pixelformat.cxx b/tests/unit/pixelformat.cxx
index 7b6087f7..46fecfb4 100644
--- a/tests/unit/pixelformat.cxx
+++ b/tests/unit/pixelformat.cxx
@@ -108,6 +108,12 @@ int main(int argc, char** argv)
doTest(true, 32, 16, false, true, 255, 255, 255, 0, 8, 16);
+ /* Invalid shift values */
+
+ doTest(true, 32, 24, false, true, 255, 255, 255, 25, 8, 16);
+ doTest(true, 32, 24, false, true, 255, 255, 255, 0, 25, 16);
+ doTest(true, 32, 24, false, true, 255, 255, 255, 0, 8, 25);
+
/* Overlapping channels */
doTest(true, 32, 24, false, true, 255, 255, 255, 0, 7, 16);
--
2.16.4