From 0930cb3021b8078b34cf216e79eb8608d017864f Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Sat, 13 Oct 2018 22:03:02 +1030 Subject: [PATCH] _bfd_clear_contents bounds checking This PR shows a fuzzed binary triggering a segfault via a bad relocation in .debug_line. It turns out that unlike normal relocations applied to a section, the linker applies those with symbols from discarded sections via _bfd_clear_contents without checking that the relocation is within the section bounds. The same thing now happens when reading debug sections since commit a4cd947aca23, the PR23425 fix. PR 23770 PR 23425 * reloc.c (_bfd_clear_contents): Replace "location" param with "buf" and "off". Bounds check "off". Return status. * cofflink.c (_bfd_coff_generic_relocate_section): Update _bfd_clear_contents call. * elf-bfd.h (RELOC_AGAINST_DISCARDED_SECTION): Likewise. * elf32-arc.c (elf_arc_relocate_section): Likewise. * elf32-i386.c (elf_i386_relocate_section): Likewise. * elf32-metag.c (metag_final_link_relocate): Likewise. * elf32-nds32.c (nds32_elf_get_relocated_section_contents): Likewise. * elf32-ppc.c (ppc_elf_relocate_section): Likewise. * elf32-visium.c (visium_elf_relocate_section): Likewise. * elf64-ppc.c (ppc64_elf_relocate_section): Likewise. * elf64-x86-64.c *(elf_x86_64_relocate_section): Likewise. * libbfd-in.h (_bfd_clear_contents): Update prototype. * libbfd.h: Regenerate. Upstream-Status: Backport CVE: CVE-2018-18605 Signed-off-by: Zhixiong Chi --- bfd/ChangeLog | 20 ++++++++++++++++++++ bfd/cofflink.c | 2 +- bfd/elf-bfd.h | 2 +- bfd/elf32-arc.c | 2 +- bfd/elf32-i386.c | 2 +- bfd/elf32-metag.c | 2 +- bfd/elf32-nds32.c | 8 ++++---- bfd/elf32-ppc.c | 2 +- bfd/elf32-visium.c | 2 +- bfd/elf64-ppc.c | 2 +- bfd/elf64-x86-64.c | 2 +- bfd/libbfd-in.h | 4 ++-- bfd/libbfd.h | 4 ++-- bfd/reloc.c | 19 +++++++++++++------ 14 files changed, 50 insertions(+), 23 deletions(-) --- a/bfd/cofflink.c +++ b/bfd/cofflink.c @@ -3080,7 +3080,7 @@ _bfd_coff_generic_relocate_section (bfd if (sec != NULL && discarded_section (sec)) { _bfd_clear_contents (howto, input_bfd, input_section, - contents + (rel->r_vaddr - input_section->vma)); + contents, rel->r_vaddr - input_section->vma); continue; } --- a/bfd/elf-bfd.h +++ b/bfd/elf-bfd.h @@ -2811,7 +2811,7 @@ extern asection _bfd_elf_large_com_secti { \ int i_; \ _bfd_clear_contents (howto, input_bfd, input_section, \ - contents + rel[index].r_offset); \ + contents, rel[index].r_offset); \ \ if (bfd_link_relocatable (info) \ && (input_section->flags & SEC_DEBUGGING)) \ --- a/bfd/elf32-arc.c +++ b/bfd/elf32-arc.c @@ -1552,7 +1552,7 @@ elf_arc_relocate_section (bfd * outp if (sec != NULL && discarded_section (sec)) { _bfd_clear_contents (howto, input_bfd, input_section, - contents + rel->r_offset); + contents, rel->r_offset); rel->r_info = 0; rel->r_addend = 0; --- a/bfd/elf32-i386.c +++ b/bfd/elf32-i386.c @@ -2197,7 +2197,7 @@ elf_i386_relocate_section (bfd *output_b if (sec != NULL && discarded_section (sec)) { _bfd_clear_contents (howto, input_bfd, input_section, - contents + rel->r_offset); + contents, rel->r_offset); wrel->r_offset = rel->r_offset; wrel->r_info = 0; wrel->r_addend = 0; --- a/bfd/elf32-metag.c +++ b/bfd/elf32-metag.c @@ -1396,7 +1396,7 @@ metag_final_link_relocate (reloc_howto_t rel, relend, howto, contents) \ { \ _bfd_clear_contents (howto, input_bfd, input_section, \ - contents + rel->r_offset); \ + contents, rel->r_offset); \ \ if (bfd_link_relocatable (info) \ && (input_section->flags & SEC_DEBUGGING)) \ --- a/bfd/elf32-nds32.c +++ b/bfd/elf32-nds32.c @@ -12582,14 +12582,14 @@ nds32_elf_get_relocated_section_contents symbol = *(*parent)->sym_ptr_ptr; if (symbol->section && discarded_section (symbol->section)) { - bfd_byte *p; + bfd_vma off; static reloc_howto_type none_howto = HOWTO (0, 0, 0, 0, FALSE, 0, complain_overflow_dont, NULL, "unused", FALSE, 0, 0, FALSE); - p = data + (*parent)->address * bfd_octets_per_byte (input_bfd); - _bfd_clear_contents ((*parent)->howto, input_bfd, input_section, - p); + off = (*parent)->address * bfd_octets_per_byte (input_bfd); + _bfd_clear_contents ((*parent)->howto, input_bfd, + input_section, data, off); (*parent)->sym_ptr_ptr = bfd_abs_section_ptr->symbol_ptr_ptr; (*parent)->addend = 0; (*parent)->howto = &none_howto; --- a/bfd/elf32-ppc.c +++ b/bfd/elf32-ppc.c @@ -8232,7 +8232,7 @@ ppc_elf_relocate_section (bfd *output_bf howto = ppc_elf_howto_table[r_type]; _bfd_clear_contents (howto, input_bfd, input_section, - contents + rel->r_offset); + contents, rel->r_offset); wrel->r_offset = rel->r_offset; wrel->r_info = 0; wrel->r_addend = 0; --- a/bfd/elf32-visium.c +++ b/bfd/elf32-visium.c @@ -621,7 +621,7 @@ visium_elf_relocate_section (bfd *output or sections discarded by a linker script, we just want the section contents zeroed. Avoid any special processing. */ _bfd_clear_contents (howto, input_bfd, input_section, - contents + rel->r_offset); + contents, rel->r_offset); rel->r_info = 0; rel->r_addend = 0; --- a/bfd/elf64-ppc.c +++ b/bfd/elf64-ppc.c @@ -14074,7 +14074,7 @@ ppc64_elf_relocate_section (bfd *output_ { _bfd_clear_contents (ppc64_elf_howto_table[r_type], input_bfd, input_section, - contents + rel->r_offset); + contents, rel->r_offset); wrel->r_offset = rel->r_offset; wrel->r_info = 0; wrel->r_addend = 0; --- a/bfd/elf64-x86-64.c +++ b/bfd/elf64-x86-64.c @@ -2490,7 +2490,7 @@ elf_x86_64_relocate_section (bfd *output if (sec != NULL && discarded_section (sec)) { _bfd_clear_contents (howto, input_bfd, input_section, - contents + rel->r_offset); + contents, rel->r_offset); wrel->r_offset = rel->r_offset; wrel->r_info = 0; wrel->r_addend = 0; --- a/bfd/libbfd-in.h +++ b/bfd/libbfd-in.h @@ -696,8 +696,8 @@ extern bfd_reloc_status_type _bfd_reloca (reloc_howto_type *, bfd *, bfd_vma, bfd_byte *) ATTRIBUTE_HIDDEN; /* Clear a given location using a given howto. */ -extern void _bfd_clear_contents - (reloc_howto_type *, bfd *, asection *, bfd_byte *) ATTRIBUTE_HIDDEN; +extern bfd_reloc_status_type _bfd_clear_contents + (reloc_howto_type *, bfd *, asection *, bfd_byte *, bfd_vma) ATTRIBUTE_HIDDEN; /* Link stabs in sections in the first pass. */ --- a/bfd/libbfd.h +++ b/bfd/libbfd.h @@ -701,8 +701,8 @@ extern bfd_reloc_status_type _bfd_reloca (reloc_howto_type *, bfd *, bfd_vma, bfd_byte *) ATTRIBUTE_HIDDEN; /* Clear a given location using a given howto. */ -extern void _bfd_clear_contents - (reloc_howto_type *, bfd *, asection *, bfd_byte *) ATTRIBUTE_HIDDEN; +extern bfd_reloc_status_type _bfd_clear_contents + (reloc_howto_type *, bfd *, asection *, bfd_byte *, bfd_vma) ATTRIBUTE_HIDDEN; /* Link stabs in sections in the first pass. */ --- a/bfd/reloc.c +++ b/bfd/reloc.c @@ -1613,16 +1613,22 @@ _bfd_relocate_contents (reloc_howto_type relocations against discarded symbols, to make ignorable debug or unwind information more obvious. */ -void +bfd_reloc_status_type _bfd_clear_contents (reloc_howto_type *howto, bfd *input_bfd, asection *input_section, - bfd_byte *location) + bfd_byte *buf, + bfd_vma off) { int size; bfd_vma x = 0; + bfd_byte *location; + + if (!bfd_reloc_offset_in_range (howto, input_bfd, input_section, off)) + return bfd_reloc_outofrange; /* Get the value we are going to relocate. */ + location = buf + off; size = bfd_get_reloc_size (howto); switch (size) { @@ -1681,6 +1687,7 @@ _bfd_clear_contents (reloc_howto_type *h #endif break; } + return bfd_reloc_ok; } /* @@ -8268,14 +8275,14 @@ bfd_generic_get_relocated_section_conten if (symbol->section && discarded_section (symbol->section)) { - bfd_byte *p; + bfd_vma off; static reloc_howto_type none_howto = HOWTO (0, 0, 0, 0, FALSE, 0, complain_overflow_dont, NULL, "unused", FALSE, 0, 0, FALSE); - p = data + (*parent)->address * bfd_octets_per_byte (input_bfd); - _bfd_clear_contents ((*parent)->howto, input_bfd, input_section, - p); + off = (*parent)->address * bfd_octets_per_byte (input_bfd); + _bfd_clear_contents ((*parent)->howto, input_bfd, + input_section, data, off); (*parent)->sym_ptr_ptr = bfd_abs_section_ptr->symbol_ptr_ptr; (*parent)->addend = 0; (*parent)->howto = &none_howto;