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| author | Dan Sinclair <dsinclair@chromium.org> | 2017-05-08 14:16:51 -0400 |
|---|---|---|
| committer | Chromium commit bot <commit-bot@chromium.org> | 2017-05-08 18:38:02 +0000 |
| commit | 486f141ed1fa5b92f59d403c4b549ede2ea1a2c8 (patch) | |
| tree | e91cc72d308c7e3ffa5e40403157de54568b5d23 | |
| parent | 1ef04c9bc0c19dd815f64ec48e7eef106cf88b49 (diff) | |
| download | pdfium-486f141ed1fa5b92f59d403c4b549ede2ea1a2c8.tar.xz | |
Check bits to decode will fit before decoding
When decoding the CPDF_HintTable we read the dwDeltaGroupLen value out
of the input stream which is a 16bit number. That value is then passed
in to read a uint32_t of the object number. If we have a group length of
> 32 bits we'll cause an undefined shift when we attempt to shift right
more then 32 bits.
This Cl bails out early if the dwDeltaGroupLen value is > 32 in order to
stop the undefined shifts.
Bug: chromium:718505
Change-Id: I919d6f4cd19826094a5e44d3a65d758029f5c236
Reviewed-on: https://pdfium-review.googlesource.com/5090
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>
| -rw-r--r-- | core/fpdfapi/parser/cpdf_hint_tables.cpp | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/core/fpdfapi/parser/cpdf_hint_tables.cpp b/core/fpdfapi/parser/cpdf_hint_tables.cpp index 24abf5dd13..6a84143f9e 100644 --- a/core/fpdfapi/parser/cpdf_hint_tables.cpp +++ b/core/fpdfapi/parser/cpdf_hint_tables.cpp @@ -290,6 +290,11 @@ bool CPDF_HintTables::ReadSharedObjHintTable(CFX_BitStream* hStream, // greatest and least length of a shared object group, in bytes. uint32_t dwDeltaGroupLen = hStream->GetBits(16); + // Trying to decode more than 32 bits isn't going to work when we write into + // a uint32_t. + if (dwDeltaGroupLen > 31) + return false; + if (dwFirstSharedObjNum >= CPDF_Parser::kMaxObjectNumber || m_nFirstPageSharedObjs >= CPDF_Parser::kMaxObjectNumber || dwSharedObjTotal >= CPDF_Parser::kMaxObjectNumber) { |