[PATCH] D63877: Avoid infinite loop with asan interception

[Julian Lettner via Phabricator via llvm-commits]

yln added inline comments.


================
Comment at: compiler-rt/lib/interception/interception_linux.cc:49
     // RTLD_DEFAULT.
     addr = dlsym(RTLD_DEFAULT, name);
+
----------------
yln wrote:
> Do we understand why we need still want the pointer, even if we don't intercept functions? Or is the comment wrong?
> https://reviews.llvm.org/D39779
> 
> I intended to change `InterceptFunction` to return true only on when "interception was successful", but I missed this case here.
> > If the lookup using RTLD_NEXT failed ...  we cannot intercept this function.
> Currently, we still return true, because we got an address `addr && (func == wrapper)`.
> 
> The original patch added a test that checks:
> ```
> // Tests that ubsan can detect errors on Android if libc appears before the
> // runtime in the library search order, which means that we cannot intercept
> // symbols.
> ```
> It's not obvious to me why we need to lookup the pointer if none of our interceptors run!?
Just to be clear, I am suggesting to try to remove the branch with `dlsym(RTLD_DEFAULT, ...)` altogether to find out the reason why it is there, but I don't want to block you on this.
LGTM; please get the okay from Vitaly.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D63877/new/

https://reviews.llvm.org/D63877