Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

We need to use library interposition instead of mach_override on Mac OS. #64

Closed
ramosian-glider opened this issue Aug 31, 2015 · 7 comments
Closed

We need to use library interposition instead of mach_override on Mac OS. #64

ramosian-glider opened this issue Aug 31, 2015 · 7 comments
Labels
OpSys-OSX Priority-High ProjectAddressSanitizer Status-Fixed Type-Enhancement

Comments

@ramosian-glider
Copy link
Member

Originally reported on Google Code with ID 64

The interposition hack is described in Amit Singh's "Mac OS X Internals" and works as
follows.

$ cat t.c 
#include <stdio.h>
#include <string.h>
const char kStr[] = "Hello world!";
int main() {
  char *dup = strdup(kStr);
  printf("dup: %s\n", dup);
  printf("strlen(dup): %d\n", strlen(dup));
  return 0;
}
$ gcc t.c -o t
...
$ ./t
dup: Hello world!
strlen(dup): 12


$ cat v.cc 
#include <unistd.h>
#include <string.h>

size_t my_strlen(const char *_) {
  return 4;
}

struct interpose_substitution {
  const void* replacement;
  const void* original;
};

#define INTERPOSE_FUNCTION(function) \
    { reinterpret_cast<const void*>(my_##function), \
      reinterpret_cast<const void*>(function) }

__attribute__((used))
const interpose_substitution substitutions[]
    __attribute__((section("__DATA, __interpose"))) = {
  INTERPOSE_FUNCTION(strlen),
};

$ g++ v.cc -dynamiclib -o v.dylib

$ DYLD_INSERT_LIBRARIES=`pwd`/v.dylib ./t
dup: Hell
strlen(dup): 4

Reported by ramosian.glider on 2012-04-13 15:16:56
@ramosian-glider
Copy link
Member Author 

Related discussion at Chromium (which uses both): http://code.google.com/p/chromium/issues/detail?id=99879

Pros and cons.

mach_override:
+ already works
+ same approach will allow to handle syscalls
- may need to extend manually for new functions
- makes code pages unshareable

__interpose:
+ easy to add new functions
- this is LD_PRELOAD essentially (need to check if we can do it in the binary)
- could be problematic to factor the wrappers into a separate .dylib (otherwise the
whole runtime will be preloaded)

Reported by ramosian.glider on 2012-04-13 15:37:40

  • Labels added: Type-Enhancement
  • Labels removed: Type-Defect

@ramosian-glider
Copy link
Member Author 

Status update: currently (LLVM r166922) we build and install the dynamic version of
ASan runtime on OS X, although the -faddress-sanitizer flag still links the program
with the static one. The dynamic runtime allows us to run Chrome tests and Chrome itself
on OS X 10.6--10.8. It's also possible to run some Chrome tests on the iOS simulator,
but it's unclear yet whether this approach works with real iOS devices.

Reported by ramosian.glider on 2012-10-29 11:41:00

  • Labels added: Priority-High
  • Labels removed: Priority-Medium

@ramosian-glider
Copy link
Member Author

Reported by ramosian.glider on 2012-10-29 11:50:20

@ramosian-glider
Copy link
Member Author

Reported by glider@chromium.org on 2013-01-17 12:42:40

  • Blocking: #170629

@ramosian-glider
Copy link
Member Author 

http://llvm-reviews.chandlerc.com/D216 and http://llvm-reviews.chandlerc.com/D223 are
the two changelists to enable the new dynamic runtime.

Reported by ramosian.glider on 2013-01-18 16:57:49

@ramosian-glider
Copy link
Member Author 

The dynamic runtime is now the default one. ASan doesn't use mach_override anymore.

Reported by ramosian.glider on 2013-02-07 16:00:52

  • Status changed: Fixed

@ramosian-glider
Copy link
Member Author 

Adding Project:AddressSanitizer as part of GitHub migration.

Reported by ramosian.glider on 2015-07-30 09:12:59

  • Labels added: ProjectAddressSanitizer

@ramosian-glider ramosian-glider mentioned this issue Aug 31, 2015
Closed
@oviano oviano mentioned this issue Mar 31, 2020
Open
@UjjwalChitransh UjjwalChitransh mentioned this issue Apr 3, 2024
Open
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
OpSys-OSX Priority-High ProjectAddressSanitizer Status-Fixed Type-Enhancement
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
1 participant
@ramosian-glider