Fix a crasher issue due to invalid 'bits per component' in PDF

Fix a crasher issue due to invalid 'bits per component' in PDF

BUG=382820
R=palmer@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/d7db790

[palmer, 2014-07-07 19:36:04]

https://codereview.chromium.org/349853003/diff/1/core/src/fpdfapi/fpdf_render...
File core/src/fpdfapi/fpdf_render/fpdf_render_loadimage.cpp (right):

https://codereview.chromium.org/349853003/diff/1/core/src/fpdfapi/fpdf_render...
core/src/fpdfapi/fpdf_render/fpdf_render_loadimage.cpp:1189: FX_DWORD src_pitch
= (src_width * bpc * m_nComponents + 7) / 8;
All the arithmetic in this function looks dangerous. Can you explain why it's
safe, or use CheckedNumeric?

[jun_fang, 2014-07-07 21:14:09]

https://codereview.chromium.org/349853003/diff/1/core/src/fpdfapi/fpdf_render...
File core/src/fpdfapi/fpdf_render/fpdf_render_loadimage.cpp (right):

https://codereview.chromium.org/349853003/diff/1/core/src/fpdfapi/fpdf_render...
core/src/fpdfapi/fpdf_render/fpdf_render_loadimage.cpp:1189: FX_DWORD src_pitch
= (src_width * bpc * m_nComponents + 7) / 8;
On 2014/07/07 19:36:04, Chromium Palmer wrote:
> All the arithmetic in this function looks dangerous. Can you explain why it's
> safe, or use CheckedNumeric?

This fix is used for that crashing issue. I already noticed the arithmetic in
this function is not safe. I suggest to raise another but to track it. It is
clearer than fixing two issues in a bug.

[palmer, 2014-07-07 21:21:42]

> This fix is used for that crashing issue. I already noticed the arithmetic in
> this function is not safe. I suggest to raise another but to track it. It is
> clearer than fixing two issues in a bug.

OK. CC me on that bug if you would, please. Thanks!

[palmer, 2014-07-07 21:22:17]

LGTM.

[jun_fang, 2014-07-07 21:36:49]

Committed patchset #1 manually as rd7db790 (presubmit successful).