command_buffer: Avoid uninitialized read in ShaderTranslatorCache

command_buffer: Avoid uninitialized read in ShaderTranslatorCache

The key in ShaderTranslatorCache std::map is copied with memcpy and
compared with memcmp. However, the key is a class that does not
guarantee not having any padding.

Padding in ShBuiltInResources causes the comparison be invalid. Valgrind
reports uninitialized reads for this.

Fix by preserving usage of memcmp. Initialize the object
with memset. This should write any possible padding data to a
well-defined state.

Depends on an ANGLE fix where ShBuiltInResources is similarly
initialized with memset. The resource data is copied to the key
implicitly, and this may or may not copy the padding.

Committed: https://crrev.com/d67d827a4f58eb06fecc3aa396683495bec7c0dd
Cr-Commit-Position: refs/heads/master@{#303817}

[Kimmo Kinnunen, 2014-10-15 12:23:51]

kkinnunen@nvidia.com changed reviewers:
+ piman@chromium.org

[Kimmo Kinnunen, 2014-10-15 12:23:52]

Not a fan of memcpy tricks, but it appears the original author must have had
some reason doing it, so trying to preserve it.

The ANGLE fix this one depends on:
https://chromium-review.googlesource.com/#/c/223431/

[piman, 2014-10-15 16:21:38]

LGTM. I'm not sure there was a good reason for memcpy. The cache is used when
compiling shaders, I don't think micro-optimizating the copy constructor or
comparators is significant.

[Kimmo Kinnunen, 2014-10-24 05:40:25]

The CQ bit was checked by kkinnunen@nvidia.com

[commit-bot: I haz the power, 2014-10-24 05:41:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/654253002/1

[commit-bot: I haz the power, 2014-10-24 05:43:33]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-10-24 05:43:33]

Try jobs failed on following builders:
  linux_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu/builds/...)
  mac_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/mac_gpu/builds/73008)
  win_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu/builds/77937)
  android_arm64_dbg_recipe on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_arm64_d...)
  android_chromium_gn_compile_dbg on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)
  android_chromium_gn_compile_rel on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)
  android_clang_dbg_recipe on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_clang_d...)
  chromium_presubmit on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)
  linux_chromium_compile_dbg_32 on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  win8_chromium_rel on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_rel...)

[Kimmo Kinnunen, 2014-10-24 06:00:12]

The CQ bit was checked by kkinnunen@nvidia.com

[commit-bot: I haz the power, 2014-10-24 06:01:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/654253002/20001

[commit-bot: I haz the power, 2014-10-24 06:27:33]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-10-24 06:27:34]

Try jobs failed on following builders:
  linux_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu_trigger...)

[Kimmo Kinnunen, 2014-11-12 08:39:27]

The CQ bit was checked by kkinnunen@nvidia.com

[commit-bot: I haz the power, 2014-11-12 08:39:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/654253002/40001

[commit-bot: I haz the power, 2014-11-12 09:27:33]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-11-12 09:27:35]

Try jobs failed on following builders:
  win_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu/builds/85338)

[Kimmo Kinnunen, 2014-11-12 10:09:30]

The CQ bit was checked by kkinnunen@nvidia.com

[commit-bot: I haz the power, 2014-11-12 10:09:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/654253002/60001

[commit-bot: I haz the power, 2014-11-12 11:09:56]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2014-11-12 11:10:36]

Patchset 4 (id:??) landed as
https://crrev.com/d67d827a4f58eb06fecc3aa396683495bec7c0dd
Cr-Commit-Position: refs/heads/master@{#303817}