[Bug sanitizer/69147] [5 Regression] Several hundred asan failures with 5.3.1 on x86_64-apple-darwin15

[chefmax at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69147

--- Comment #10 from Maxim Ostapenko <chefmax at gcc dot gnu.org> ---
Created attachment 37310
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37310&action=edit
Proposed fix.

« El Capitan » is OS X 10.11, right? So, this is my vision of the problem:

In OS X 10.11+ or iOS 9.0+, dyld will interpose even if DYLD_INSERT_LIBRARIES
is not set. This means, that it's not safe to use "setenv" function to set
DYLD_INSERT_LIBRARIES in MaybeReexec, because ASan interceptors already
established and we can easily end up with something like this:

AsanInitInternal -> MaybeReexec -> setenv -> some intercepted function (say,
memmove) -> BOOM.

In fact, there is no need to reexec at all on such platforms, because we
already have working interceptors.

Upstream ASan already has the fix, attaching adapted cherry-picked commit.
Could you try it?