Re: [Tinycc-devel] -fsanitizer=address

[Pascal Cuoq]

Hello,

On 12 Jun 2019, at 21:21, Mike <address@hidden> wrote:

I've run "make test" under -fsanitize=address and got the same report for several failed tests:

This appears to be caused by an offset into a dynamically allocated block being assigned to sym in build_got_entries at line 1041:

            sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];

And this dynamically allocated block being realloc'ed as a result of calling build_got(s1) at line 1102:

                build_got(s1);

Bearing in mind that we keep using sym at line 1108:

            attr = put_got_entry(s1, reloc_type, sym->st_size, sym->st_info,

                                 sym_index);

I have no idea what I am doing, but I applied the following patch and it seems to have fixed the dangling pointer, according to the tool I use (not ASan).

diff --git a/tccelf.c b/tccelf.c

index e5f6c42..6ddfb9f 100644

--- a/tccelf.c

+++ b/tccelf.c

@@ -1098,8 +1098,10 @@ ST_FUNC void build_got_entries(TCCState *s1)

             } else

                 reloc_type = R_GLOB_DAT;

 

-            if (!s1->got)

+            if (!s1->got) {

                 build_got(s1);

+                sym = &((ElfW(Sym) *)symtab_section->data)[sym_index]; //attempt

+            }

 

             if (gotplt_entry == BUILD_GOT_ONLY)

                 continue;

Would a developer confirm this is a good idea?

Pascal

dangling.patch
Description: dangling.patch