From bce964aa6c777d236fbd641f2bc7bb931cfe4bf3 Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Sun, 23 Apr 2017 11:03:34 +0930 Subject: [PATCH] PR 21412, get_reloc_section assumes .rel/.rela name for SHT_REL/RELA. This patch fixes an assumption made by code that runs for objcopy and strip, that SHT_REL/SHR_RELA sections are always named starting with a .rel/.rela prefix. I'm also modifying the interface for elf_backend_get_reloc_section, so any backend function just needs to handle name mapping. PR 21412 * elf-bfd.h (struct elf_backend_data ): Change parameters and comment. (_bfd_elf_get_reloc_section): Delete. (_bfd_elf_plt_get_reloc_section): Declare. * elf.c (_bfd_elf_plt_get_reloc_section, elf_get_reloc_section): New functions. Don't blindly skip over assumed .rel/.rela prefix. Extracted from.. (_bfd_elf_get_reloc_section): ..here. Delete. (assign_section_numbers): Call elf_get_reloc_section. * elf64-ppc.c (elf_backend_get_reloc_section): Define. * elfxx-target.h (elf_backend_get_reloc_section): Update. Upstream-Status: Backport CVE: CVE-2017-8393 Signed-off-by: Armin Kuster --- bfd/ChangeLog | 15 ++++++++++++++ bfd/elf-bfd.h | 8 ++++--- bfd/elf.c | 61 +++++++++++++++++++++++++++++++----------------------- bfd/elf64-ppc.c | 1 + bfd/elfxx-target.h | 2 +- 5 files changed, 57 insertions(+), 30 deletions(-) Index: git/bfd/elf-bfd.h =================================================================== --- git.orig/bfd/elf-bfd.h +++ git/bfd/elf-bfd.h @@ -1322,8 +1322,10 @@ struct elf_backend_data bfd_size_type (*maybe_function_sym) (const asymbol *sym, asection *sec, bfd_vma *code_off); - /* Return the section which RELOC_SEC applies to. */ - asection *(*get_reloc_section) (asection *reloc_sec); + /* Given NAME, the name of a relocation section stripped of its + .rel/.rela prefix, return the section in ABFD to which the + relocations apply. */ + asection *(*get_reloc_section) (bfd *abfd, const char *name); /* Called to set the sh_flags, sh_link and sh_info fields of OSECTION which has a type >= SHT_LOOS. Returns TRUE if the fields were initialised, @@ -2392,7 +2394,7 @@ extern bfd_boolean _bfd_elf_is_function_ extern bfd_size_type _bfd_elf_maybe_function_sym (const asymbol *, asection *, bfd_vma *); -extern asection *_bfd_elf_get_reloc_section (asection *); +extern asection *_bfd_elf_plt_get_reloc_section (bfd *, const char *); extern int bfd_elf_get_default_section_type (flagword); Index: git/bfd/elf.c =================================================================== --- git.orig/bfd/elf.c +++ git/bfd/elf.c @@ -3532,17 +3532,39 @@ bfd_elf_set_group_contents (bfd *abfd, a H_PUT_32 (abfd, sec->flags & SEC_LINK_ONCE ? GRP_COMDAT : 0, loc); } -/* Return the section which RELOC_SEC applies to. */ +/* Given NAME, the name of a relocation section stripped of its + .rel/.rela prefix, return the section in ABFD to which the + relocations apply. */ asection * -_bfd_elf_get_reloc_section (asection *reloc_sec) +_bfd_elf_plt_get_reloc_section (bfd *abfd, const char *name) +{ + /* If a target needs .got.plt section, relocations in rela.plt/rel.plt + section likely apply to .got.plt or .got section. */ + if (get_elf_backend_data (abfd)->want_got_plt + && strcmp (name, ".plt") == 0) + { + asection *sec; + + name = ".got.plt"; + sec = bfd_get_section_by_name (abfd, name); + if (sec != NULL) + return sec; + name = ".got"; + } + + return bfd_get_section_by_name (abfd, name); +} + +/* Return the section to which RELOC_SEC applies. */ + +static asection * +elf_get_reloc_section (asection *reloc_sec) { const char *name; unsigned int type; bfd *abfd; - - if (reloc_sec == NULL) - return NULL; + const struct elf_backend_data *bed; type = elf_section_data (reloc_sec)->this_hdr.sh_type; if (type != SHT_REL && type != SHT_RELA) @@ -3550,28 +3572,15 @@ _bfd_elf_get_reloc_section (asection *re /* We look up the section the relocs apply to by name. */ name = reloc_sec->name; - if (type == SHT_REL) - name += 4; - else - name += 5; + if (strncmp (name, ".rel", 4) != 0) + return NULL; + name += 4; + if (type == SHT_RELA && *name++ != 'a') + return NULL; - /* If a target needs .got.plt section, relocations in rela.plt/rel.plt - section apply to .got.plt section. */ abfd = reloc_sec->owner; - if (get_elf_backend_data (abfd)->want_got_plt - && strcmp (name, ".plt") == 0) - { - /* .got.plt is a linker created input section. It may be mapped - to some other output section. Try two likely sections. */ - name = ".got.plt"; - reloc_sec = bfd_get_section_by_name (abfd, name); - if (reloc_sec != NULL) - return reloc_sec; - name = ".got"; - } - - reloc_sec = bfd_get_section_by_name (abfd, name); - return reloc_sec; + bed = get_elf_backend_data (abfd); + return bed->get_reloc_section (abfd, name); } /* Assign all ELF section numbers. The dummy first section is handled here @@ -3833,7 +3842,7 @@ assign_section_numbers (bfd *abfd, struc if (s != NULL) d->this_hdr.sh_link = elf_section_data (s)->this_idx; - s = get_elf_backend_data (abfd)->get_reloc_section (sec); + s = elf_get_reloc_section (sec); if (s != NULL) { d->this_hdr.sh_info = elf_section_data (s)->this_idx; Index: git/bfd/elf64-ppc.c =================================================================== --- git.orig/bfd/elf64-ppc.c +++ git/bfd/elf64-ppc.c @@ -121,6 +121,7 @@ static bfd_vma opd_entry_value #define elf_backend_special_sections ppc64_elf_special_sections #define elf_backend_merge_symbol_attribute ppc64_elf_merge_symbol_attribute #define elf_backend_merge_symbol ppc64_elf_merge_symbol +#define elf_backend_get_reloc_section bfd_get_section_by_name /* The name of the dynamic interpreter. This is put in the .interp section. */ Index: git/bfd/elfxx-target.h =================================================================== --- git.orig/bfd/elfxx-target.h +++ git/bfd/elfxx-target.h @@ -706,7 +706,7 @@ #endif #ifndef elf_backend_get_reloc_section -#define elf_backend_get_reloc_section _bfd_elf_get_reloc_section +#define elf_backend_get_reloc_section _bfd_elf_plt_get_reloc_section #endif #ifndef elf_backend_copy_special_section_fields Index: git/bfd/ChangeLog =================================================================== --- git.orig/bfd/ChangeLog +++ git/bfd/ChangeLog @@ -1,3 +1,18 @@ +2017-04-23 Alan Modra + + PR 21412 + * elf-bfd.h (struct elf_backend_data ): Change + parameters and comment. + (_bfd_elf_get_reloc_section): Delete. + (_bfd_elf_plt_get_reloc_section): Declare. + * elf.c (_bfd_elf_plt_get_reloc_section, elf_get_reloc_section): + New functions. Don't blindly skip over assumed .rel/.rela prefix. + Extracted from.. + (_bfd_elf_get_reloc_section): ..here. Delete. + (assign_section_numbers): Call elf_get_reloc_section. + * elf64-ppc.c (elf_backend_get_reloc_section): Define. + * elfxx-target.h (elf_backend_get_reloc_section): Update. + 2017-04-04 Nick Clifton PR binutils/21342