[Mono-devel-list] [PATCH] Improper free of return-value string pointers from unmanaged calls

[Steven Brown]

Mono improperly tries to free string pointers passed as the return value 
of unmanaged calls via P/Invoke.  This removes the code that frees that 
string pointer.

I've attached an example of the kind of bug this fixes.  Can be tried like:
g++ foo.cc -shared -o foo.so && mcs Test.cs && LD_LIBRARY_PATH=. mono 
Test.exe

If you're running valgrind, you'll see something like:

==15815== Thread 3:
==15815== Invalid free() / delete / delete[]
==15815==    at 0x40027E7A: free (vg_replace_malloc.c:231)
==15815==    by 0x403EB8CD: g_free (in /usr/lib/libglib-2.0.so.0.0.1)
==15815==    by 0x418EC4E2: ???
==15815==    by 0x418EC53D: ???
==15815==    Address 0x418F5728 is not stack'd, malloc'd or free'd

If you aren't, it might or might not crash 
(System.NullReferenceException from __icall_wrapper_g_free) depending on 
your luck.


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