While making crashpad_minidump_test run in Chromium’s try- and buildbots
(https://crbug.com/779790), crashes in the
MinidumpThreadWriter.OneThread_AMD64_Stack test were observed in 32-bit
x86 Windows builds produced by Clang in the release configuration. These
crashes occurred in crashpad::test::InitializeMinidumpContextAMD64,
which heap-allocates a MinidumpContextAMD64Writer object. These objects
have an alignment requirement of 16, based on the alignment requirement
of their MinidumpContextAMD64 member.
Although this problem was never observed with MSVC, Clang was making use
of the known strict alignment and producing code that depended on it.
This code crashed if the requirement was not met. MSVC had raised a
warning about this usage (C4316), but the warning was disabled as it did
not appear to have any ill effect on code produced by that compiler.
The problem surfaced in test code, but heap-allocated
MinidumpContextAMD64Writer objects are created in non-test code as well.
The impact is limited, because a 32-bit Windows Crashpad handler would
not have a need to allocate one of these objects.
As a fix, MinidumpContextAMD64Writer is given a custom allocation
function (a static “operator new()” member and matching “operator
delete()”) that returns properly aligned memory.
Change-Id: I0cb924da91716eb01b88ec2ae952a69262cc2de6
Reviewed-on: https://chromium-review.googlesource.com/746539
Reviewed-by: Leonard Mosescu <mosescu@chromium.org>
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