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.
Index: ldso/ldso/ldso.c
===================================================================
--- ldso/ldso/ldso.c (revision 20342)
+++ ldso/ldso/ldso.c (working copy)
@@ -286,6 +286,7 @@
_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))
@@ -294,7 +295,13 @@
(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
#ifndef ALLOW_ZERO_PLTGOT
--
Joseph S. Myers
[EMAIL PROTECTED]
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