ucrtbase.dll appears to be built with some kind of cross-module
inlining, because there are calls to imported Heap* routines sprinkled
throughout the code. This inlining defeats our attempts to hotpatch
malloc, _malloc_base, and related functions. Failing to intercept an
allocation or deallocation results in a crash when the program attempts
to deallocate or reallocate memory with the wrong allocator.
This change patches the IAT of ucrtbase.dll to replace the addresses of
the imported Heap* functions with implementations provided by ASan. We
don't globally intercept the win32 Heap* functions because they are
typically used by system DLLs that run before ASan initializes.
Eventually, we may want to intercept them, but for now I think this is
the minimal change that will keep ASan stable.
Reviewers: samsonov
Differential Revision: http://reviews.llvm.org/D18413
llvm-svn: 264327
This is necessary to support the dynamic CRT (/MD) with VS2015. In
VS2015, these symbols are no longer imported from a DLL, they provided
statically by msvcrt.lib. This means our approach of hotpatching the DLL
no longer works.
By exporting the symbols, we end up relying on the same mechanism that
we use to intercept symbols in the static CRT (/MT) case. The ASan
runtime always needs to appear first on the link line, and the linker
searches for symbol definitions from left to right. This means we can
stop hotpatching operator new and delete in the CRT, which is nice.
I think that the only reason we weren't exporting the symbols already is
because MSVC doesn't allow you to do it directly with
__declspec(dllexport). Instead, we can use
`#pragma comment(linker, "/export:foo")`, which is most of what the
attribute does under the hood. It does mean we have to write down the
mangled names of the operators, but that's not too bad.
llvm-svn: 264190
There are some places in the CRT (such as mbctype) that directly call
_malloc_base. If you are incrementally linking a binary with ASan from
before this change, this change appears to result in a linker error.
Retrying the link succeeds for some reason.
llvm-svn: 264005
MSanDR is a dynamic instrumentation tool that can instrument the code
(prebuilt libraries and such) that could not be instrumented at compile time.
This code is unused (to the best of our knowledge) and unmaintained, and
starting to bit-rot.
llvm-svn: 222232
Invoke a fatal stack trace unwinder when ASan prints allocator-relevant
error reports (double-free, alloc-dealloc-mismatch, invalid-free).
Thus we'll be able to print complete stack trace even if allocation/free
stacks are not stored (malloc_context_size=0).
Based on the patch by Yuri Gribov!
llvm-svn: 194579
Reid Kleckner