[Bug gold/24462] New: Gold linker does not handle symbol versioning properly

[olim at ucla dot edu]

https://sourceware.org/bugzilla/show_bug.cgi?id=24462

            Bug ID: 24462
           Summary: Gold linker does not handle symbol versioning properly
           Product: binutils
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gold
          Assignee: ccoutant at gmail dot com
          Reporter: olim at ucla dot edu
                CC: ian at airs dot com
  Target Milestone: ---

The gold linker does not appear to grab the correct symbol version when when
using the --wrap option and multiple versions of the same symbol are available.
For example, using `--wrap=memcpy` with the following code produces an infinite
recursion.

```
#include <string.h>

asm (".symver old_memcpy, address@hidden"); // hook old_memcpy as
address@hidden
void *old_memcpy(void *, const void *, size_t );
void *__wrap_memcpy(void *dest, const void *src, size_t n) // then export
memcpy
{
    return old_memcpy(dest, src, n);
}

int main()
{
    int v1 = 1;
    int v2 = 0;
    __wrap_memcpy(v1, v2, sizeof(v1));
    return 0;
}
```

$ gcc -fuse-ld=gold -Wl,--wrap=memcpy main.c
$ readelf -a a.out | grep memcpy
     5: 0000000000400660     2 FUNC    GLOBAL DEFAULT   11 __wrap_memcpy
    23: 0000000000400660     2 FUNC    GLOBAL DEFAULT   11 __wrap_memcpy

Using the BFD linker everything behaves as expected:

$ gcc -fuse-ld=bfd -Wl,--wrap=memcpy main.c
$ readelf -a a.out | grep memcpy
000000600fe0  000100000007 R_X86_64_JUMP_SLO 0000000000000000
address@hidden + 0
     1: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND address@hidden
(2)
    51: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND address@hidden
    53: 0000000000400710     5 FUNC    GLOBAL DEFAULT   13 __wrap_memcpy

Using the gold linker again, but replacing

    asm (".symver old_memcpy, address@hidden");

with

    asm (".symver old_memcpy, address@hidden");

avoid the infinite recursion, but links against the wrong version

$ readelf -a a.out | grep memcpy
000000401ff0  000200000007 R_X86_64_JUMP_SLO 0000000000000000 address@hidden
+ 0
     2: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND address@hidden
(3)
     7: 0000000000400790     5 FUNC    GLOBAL DEFAULT   13 __wrap_memcpy
    23: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND memcpy
    25: 0000000000400790     5 FUNC    GLOBAL DEFAULT   13 __wrap_memcpy

Which is linking to the memcpy in GLIBC_2.14 instead of the memcpy in
GLIBC_2.2.5. Is there a different symbol versioning syntax needed when using
the gold linker?

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