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[asan] Fix dyld version detection on OS X 

We currently have a dyld check in DyldNeedsEnvVariable that detects whether we are on a new OS X (10.11+) where we don't need to re-exec. For iOS simulator, we have a dlsym() hack that checks for a specific symbol, but this turns out to be fragile and problematic, because dlsym can sometimes call malloc(), which is not a good idea this early in the process runtime.

Let's instead of this do a direct comparison of dyld's version, which is exported in a public symbol `dyldVersionNumber`.

Differential Revision: http://reviews.llvm.org/D11719

llvm-svn: 243879
This commit is contained in:
Kuba Brecka 2015-08-03 14:48:59 +00:00
parent f607111d95
commit fe17cee960
1 changed files with 9 additions and 14 deletions
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23
compiler-rt/lib/asan/asan_mac.cc
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@ -99,21 +99,16 @@ void DisableReexec() {
reexec_disabled = true;
}
extern "C" double dyldVersionNumber;
static const double kMinDyldVersionWithAutoInterposition = 360.0;
bool DyldNeedsEnvVariable() {
// If running on OS X 10.11+ or iOS 9.0+, dyld will interpose even if
// DYLD_INSERT_LIBRARIES is not set.
#if SANITIZER_IOSSIM
// GetMacosVersion will not work for the simulator, whose kernel version
// is tied to the host. Use a weak linking hack for the simulator.
// This API was introduced in the same version of the OS as the dyld
// optimization.
// Check for presence of a symbol that is available on OS X 10.11+, iOS 9.0+.
return (dlsym(RTLD_NEXT, "mach_memory_info") == nullptr);
#else
return (GetMacosVersion() <= MACOS_VERSION_YOSEMITE);
#endif
// If running on OS X 10.11+ or iOS 9.0+, dyld will interpose even if
// DYLD_INSERT_LIBRARIES is not set. However, checking OS version via
// GetMacosVersion() doesn't work for the simulator. Let's instead check
// `dyldVersionNumber`, which is exported by dyld, against a known version
// number from the first OS release where this appeared.
return dyldVersionNumber < kMinDyldVersionWithAutoInterposition;
}
void MaybeReexec() {