glibc/elf/ifuncmod6.c
H.J. Lu 1864775abc x86: Check IFUNC definition in unrelocated executable [BZ #20019]
Calling an IFUNC function defined in unrelocated executable also leads to
segfault.  Issue a fatal error message when calling IFUNC function defined
in the unrelocated executable from a shared library.

On x86, ifuncmain6pie failed with:

[hjl@gnu-cfl-2 build-i686-linux]$ ./elf/ifuncmain6pie --direct
./elf/ifuncmain6pie: IFUNC symbol 'foo' referenced in '/export/build/gnu/tools-build/glibc-32bit/build-i686-linux/elf/ifuncmod6.so' is defined in the executable and creates an unsatisfiable circular dependency.
[hjl@gnu-cfl-2 build-i686-linux]$ readelf -rW elf/ifuncmod6.so | grep foo
00003ff4  00000706 R_386_GLOB_DAT         0000400c   foo_ptr
00003ff8  00000406 R_386_GLOB_DAT         00000000   foo
0000400c  00000401 R_386_32               00000000   foo
[hjl@gnu-cfl-2 build-i686-linux]$

Remove non-JUMP_SLOT relocations against foo in ifuncmod6.so, which
trigger the circular IFUNC dependency, and build ifuncmain6pie with
-Wl,-z,lazy.

(cherry picked from commits 6ea5b57afa
 and 7137d682eb)
2021-01-13 14:30:42 -08:00

20 lines
229 B
C

/* Test STT_GNU_IFUNC symbol reference in a shared library. */
extern int foo (void);
typedef int (*foo_p) (void);
extern foo_p foo_ptr;
foo_p
get_foo_p (void)
{
return foo_ptr;
}
int
call_foo (void)
{
return foo ();
}