Hi, May I ask how long it takes if I want to reimplement the runtime library for address sanitizer by one person? Saying that reimplementing the interfaces, interceptors and internal glibc functions. 在2021年4月13日星期二 UTC+8 下午6:52:56<Dmitry Vyukov> 写道：
> On Tue, Apr 13, 2021 at 11:55 AM Wei Chen <[email protected]> wrote: > > > > Hi all, > > > > I'm recently learning Address Sanitizer code and learned that the > runtime library is designed to replace the glibc malloc/free with our > customized ones so that we can insert red zone before and after the > allocated region. > > > > From the code, I've learned that such a replacement is implemented by > changing the runtime library load priority. By writing our malloc/free with > exactly the same function signature as the library ones, and letting our > runtime library being loaded before glibc, our malloc/free function will be > invoked by the user program. > > > > However, we are not able to invoke printf library functions anymore, > cause printf depends on malloc, therefore, each time when printf is invoked > when implementing asan runtime library, it will call our malloc instead of > library malloc. > > > > Why not just implement our malloc and free to another name, say > asan_malloc and asan_free? In that case, we can replace the malloc > invocation with asan_malloc invocation during compilation, and no need to > write a totally new printf. Is there any reason to have the same name? > > Hi Wei, > > One reason to define them with the same name is that it allows to > intercept malloc/free calls in code compiled without ASAN (e.g. libc's > getline). We won't check accesses to the buffer inside of libc, but we > will check them in the user code that uses the buffer. > Another reason is probably more important: in some cases memory is > allocated in one library and freed in another (again - getline). In > that case we may get a fatal crash/memory corruption is malloc/free > are not matching. > -- You received this message because you are subscribed to the Google Groups "address-sanitizer" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/address-sanitizer/5ecf5c2d-55ff-4644-afd7-4733cdab380en%40googlegroups.com.
