commit 8c806cf08ff928630142f769ca689f7c89bfd648
author Ryan Harrison <rharrison@chromium.org> Tue Sep 26 12:14:57 2017 -0400
committer Chromium commit bot <commit-bot@chromium.org> Tue Sep 26 20:05:13 2017 +0000
tree 983d634d4f5cdfe842f739491e2f0d50ca77a79e
parent e2df5b7305df66efbd81232d911615af60624ae3

Confirm that a global palette has data before attempting to use it

Previous implementation assumed that if the local colour palette was
not specified and the global palette had its size specified, then use
the global. If the global palette is disable, it will not have data,
but it may have a size. Technically the size is giberish in this case,
but the value is allowed to be non-zero, so isn't a sufficient check.

BUG=chromium:768089

Change-Id: Iaec15fcd65f3983056df7d56d29118a516334cd9
Reviewed-on: https://pdfium-review.googlesource.com/14819
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>

core/fxcodec/codec/fx_codec_progress.cpp

diff --git a/core/fxcodec/codec/fx_codec_progress.cpp b/core/fxcodec/codec/fx_codec_progress.cpp
index f10523c..0f2f561 100644
--- a/core/fxcodec/codec/fx_codec_progress.cpp
+++ b/core/fxcodec/codec/fx_codec_progress.cpp
@@ -625,6 +625,8 @@
   if (pal_num != 0 && pal_ptr) {
     pPalette = (uint8_t*)pal_ptr;
   } else {
+    if (!m_pGifPalette)
+      return false;
     pal_num = m_GifPltNumber;
     pPalette = m_pGifPalette;
   }
@@ -1207,6 +1209,7 @@
       while (readResult == GifDecodeStatus::Unfinished) {
         FXCODEC_STATUS error_status = FXCODEC_STATUS_ERR_FORMAT;
         if (!GifReadMoreData(pGifModule, error_status)) {
+          m_pGifContext = nullptr;
           m_status = error_status;
           return false;
         }