If uClibc's ld.so encounters text relocations in a shared library - one

containing an object built without -fpic/-fPIC - then:

* If __FORCE_SHAREABLE_TEXT_SEGMENTS__, then it gives an error "Can't
modify %s's text section. Use GCC option -fPIC for shared objects,
please.\n" and exits.

* Otherwise, it makes the library's pages writable and relocates it.

If it encounters text relocations in a position-independent executable -
one containing an object built without -fpie/-fPIE/-fpic/-fPIC - then:

* If __FORCE_SHAREABLE_TEXT_SEGMENTS__, it does nothing about making the
pages writable, leading to a crash.

* Otherwise, the loop to make the pages writable uses the same variable
ppnt as used in an outer loop, messing up that outer loop and also causing
a crash.

This patch fixes both cases, by giving an error if
__FORCE_SHAREABLE_TEXT_SEGMENTS__ and saving and restoring ppnt otherwise.
Tested in both cases on ARM EABI.

Joseph S. Myers
joseph@codesourcery.com

diff --git a/ldso/ldso/ldso.c b/ldso/ldso/ldso.c
index e1101bd..3a5fc14 100644 (file)
--- a/ldso/ldso/ldso.c
+++ b/ldso/ldso/ldso.c
@@ -286,6 +286,7 @@ void _dl_get_ready_to_run(struct elf_resolve *tpnt, DL_LOADADDR_TYPE load_addr,
                        _dl_debug_early("calling mprotect on the application program\n");
                        /* Now cover the application program. */
                        if (app_tpnt->dynamic_info[DT_TEXTREL]) {
+                               ElfW(Phdr) *ppnt_outer = ppnt;
                                ppnt = (ElfW(Phdr) *) auxvt[AT_PHDR].a_un.a_val;
                                for (i = 0; i < auxvt[AT_PHNUM].a_un.a_val; i++, ppnt++) {
                                        if (ppnt->p_type == PT_LOAD && !(ppnt->p_flags & PF_W))
@@ -294,6 +295,12 @@ void _dl_get_ready_to_run(struct elf_resolve *tpnt, DL_LOADADDR_TYPE load_addr,
                                                             (unsigned long) ppnt->p_filesz,
                                                             PROT_READ | PROT_WRITE | PROT_EXEC);
                                }
+                               ppnt = ppnt_outer;
+                       }
+#else
+                       if (app_tpnt->dynamic_info[DT_TEXTREL]) {
+                               _dl_dprintf(_dl_debug_file, "Can't modify application's text section; use the GCC option -fPIE for position-independent executables.\n");
+                               _dl_exit(1);
                        }
 #endif