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These are slightly frustrating. First, when a struct is packed, some of its fields may be underaligned. This is fine for direct access (foo.bar), but if one takes the address if the field, this creates an unaligned pointer. Dereferencing that pointer is then UB. (I'm not sure if creating that pointer is UB.) Crashpad seemingly doesn't do this, but it uses EXPECT_EQ from GTest. EXPECT_EQ seems to internally take pointers to its arguments. I'm guessing it binds them by const reference. This then trips UBSan. To avoid this, we can copy the value into a temporary before passing to EXPECT_EQ. Second, the test to divide by 0 to trigger SIGFPE is undefined behavior. The compiler is not actually obligated to trip SIGFPE. UBSan prints one of its errors instead. Instead, since this file is only built on POSIX anyway, use GCC inline assembly to do the division. That one is well-defined. Finally, casting a string to uint32_t* is undefined both by alignment and by strict aliasing (although Chromium doesn't enable the latter). Instead, type-punning should be done with memcpy. Bug: chromium:1394755 Change-Id: I79108773a04ac26f5189e7b88a0acbf62eb4401d Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/4985905 Reviewed-by: Robert Sesek <rsesek@chromium.org> Commit-Queue: David Benjamin <davidben@chromium.org>