From e133d00576f3da89e7772149e8d2b6a059d26919 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 21 Apr 2017 12:03:14 -0700 Subject: i386: Avoid dynamic symbol with GOT reference in PIE GOT reference to global symbol in PIE will lead to dynamic symbol. It becomes a problem when "time" or "times" is defined as a variable in an executable, clashing with functions of the same name in libc. If a symbol isn't undefined weak symbol, don't make it dynamic in PIE and generate R_386_RELATIVE relocation. bfd/ PR ld/21402 * elf32-i386.c (elf_i386_link_hash_entry): Add no_finish_dynamic_symbol. (elf_i386_link_hash_newfunc): Set no_finish_dynamic_symbol to 0. (elf_i386_allocate_dynrelocs): If a symbol isn't undefined weak symbol, don't make it dynamic in PIE. (elf_i386_relocate_section): If a symbol isn't dynamic in PIE, set no_finish_dynamic_symbol and generate R_386_RELATIVE relocation for R_386_GOT32 (elf_i386_finish_dynamic_symbol): Abort if no_finish_dynamic_symbol isn't 0. ld/ PR ld/21402 * testsuite/ld-elf/indirect.exp: Don't skip PIE indirect5 and indirect6 tests on i386. --- bfd/ChangeLog | 14 +++++++++++++ bfd/elf32-i386.c | 61 +++++++++++++++++++++++++++++++++++++++----------------- 2 files changed, 57 insertions(+), 18 deletions(-) (limited to 'bfd') diff --git a/bfd/ChangeLog b/bfd/ChangeLog index 4576020..ba2d134 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,5 +1,19 @@ 2017-04-21 H.J. Lu + PR ld/21402 + * elf32-i386.c (elf_i386_link_hash_entry): Add + no_finish_dynamic_symbol. + (elf_i386_link_hash_newfunc): Set no_finish_dynamic_symbol to 0. + (elf_i386_allocate_dynrelocs): If a symbol isn't undefined weak + symbol, don't make it dynamic in PIE. + (elf_i386_relocate_section): If a symbol isn't dynamic in PIE, + set no_finish_dynamic_symbol and generate R_386_RELATIVE + relocation for R_386_GOT32 + (elf_i386_finish_dynamic_symbol): Abort if no_finish_dynamic_symbol + isn't 0. + +2017-04-21 H.J. Lu + PR ld/19617 PR ld/21086 * elflink.c (elf_link_add_object_symbols): Require diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c index 7af6863..9e71974 100644 --- a/bfd/elf32-i386.c +++ b/bfd/elf32-i386.c @@ -820,6 +820,9 @@ struct elf_i386_link_hash_entry /* Symbol has non-GOT/non-PLT relocations in text sections. */ unsigned int has_non_got_reloc : 1; + /* Don't call finish_dynamic_symbol on this symbol. */ + unsigned int no_finish_dynamic_symbol : 1; + /* 0: symbol isn't ___tls_get_addr. 1: symbol is ___tls_get_addr. 2: symbol is unknown. */ @@ -959,6 +962,7 @@ elf_i386_link_hash_newfunc (struct bfd_hash_entry *entry, eh->gotoff_ref = 0; eh->has_got_reloc = 0; eh->has_non_got_reloc = 0; + eh->no_finish_dynamic_symbol = 0; eh->tls_get_addr = 2; eh->func_pointer_refcount = 0; eh->plt_got.offset = (bfd_vma) -1; @@ -2863,10 +2867,14 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf) int tls_type = elf_i386_hash_entry(h)->tls_type; /* Make sure this symbol is output as a dynamic symbol. - Undefined weak syms won't yet be marked as dynamic. */ + Undefined weak syms won't yet be marked as dynamic. + PR ld/21402: If this symbol isn't undefined weak symbol, + don't make it dynamic in PIE. */ if (h->dynindx == -1 && !h->forced_local - && !resolved_to_zero) + && !resolved_to_zero + && (h->root.type == bfd_link_hash_undefweak + || !bfd_link_pie (info))) { if (! bfd_elf_link_record_dynamic_symbol (info, h)) return FALSE; @@ -3818,6 +3826,7 @@ elf_i386_relocate_section (bfd *output_bfd, bfd_vma st_size; asection *resolved_plt; bfd_boolean resolved_to_zero; + bfd_boolean relative_reloc; r_type = ELF32_R_TYPE (rel->r_info); if (r_type == R_386_GNU_VTINHERIT @@ -4268,6 +4277,7 @@ r_386_got32: if (htab->elf.sgot == NULL) abort (); + relative_reloc = FALSE; if (h != NULL) { bfd_boolean dyn; @@ -4301,6 +4311,17 @@ r_386_got32: bfd_put_32 (output_bfd, relocation, htab->elf.sgot->contents + off); h->got.offset |= 1; + + if (h->dynindx == -1 + && !h->forced_local + && h->root.type != bfd_link_hash_undefweak + && bfd_link_pie (info)) + { + /* PR ld/21402: If this symbol isn't dynamic + in PIE, generate R_386_RELATIVE here. */ + eh->no_finish_dynamic_symbol = 1; + relative_reloc = TRUE; + } } } else @@ -4322,27 +4343,29 @@ r_386_got32: { bfd_put_32 (output_bfd, relocation, htab->elf.sgot->contents + off); + local_got_offsets[r_symndx] |= 1; if (bfd_link_pic (info)) - { - asection *s; - Elf_Internal_Rela outrel; - - s = htab->elf.srelgot; - if (s == NULL) - abort (); - - outrel.r_offset = (htab->elf.sgot->output_section->vma - + htab->elf.sgot->output_offset - + off); - outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE); - elf_append_rel (output_bfd, s, &outrel); - } - - local_got_offsets[r_symndx] |= 1; + relative_reloc = TRUE; } } + if (relative_reloc) + { + asection *s; + Elf_Internal_Rela outrel; + + s = htab->elf.srelgot; + if (s == NULL) + abort (); + + outrel.r_offset = (htab->elf.sgot->output_section->vma + + htab->elf.sgot->output_offset + + off); + outrel.r_info = ELF32_R_INFO (0, R_386_RELATIVE); + elf_append_rel (output_bfd, s, &outrel); + } + if (off >= (bfd_vma) -2) abort (); @@ -5321,6 +5344,8 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd, plt_entry_size = GET_PLT_ENTRY_SIZE (output_bfd); eh = (struct elf_i386_link_hash_entry *) h; + if (eh->no_finish_dynamic_symbol) + abort (); /* We keep PLT/GOT entries without dynamic PLT/GOT relocations for resolved undefined weak symbols in executable so that their -- cgit v1.1