Backported of: From 18cc11a2771d9e40180485da9a4fb660c03efac3 Mon Sep 17 00:00:00 2001 From: Nick Clifton Date: Wed, 5 Feb 2025 14:31:10 +0000 Subject: [PATCH] Prevent illegal memory access when checking relocs in a corrupt ELF binary. PR 32641 Upstream-Status: Backport [import from ubuntu https://git.launchpad.net/ubuntu/+source/binutils/tree/debian/patches/CVE-2025-1181-pre.patch?h=ubuntu/jammy-security Upstream commit https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=18cc11a2771d9e40180485da9a4fb660c03efac3] CVE: CVE-2025-1181 Signed-off-by: Vijay Anusuri --- bfd/elf-bfd.h | 3 +++ bfd/elf64-x86-64.c | 10 +++++----- bfd/elflink.c | 24 ++++++++++++++++++++++++ bfd/elfxx-x86.c | 20 +++++++------------- 4 files changed, 39 insertions(+), 18 deletions(-) Index: binutils-2.38/bfd/elf-bfd.h =================================================================== --- binutils-2.38.orig/bfd/elf-bfd.h +++ binutils-2.38/bfd/elf-bfd.h @@ -3007,6 +3007,9 @@ extern bool _bfd_elf_maybe_set_textrel extern bool _bfd_elf_add_dynamic_tags (bfd *, struct bfd_link_info *, bool); +extern struct elf_link_hash_entry * _bfd_elf_get_link_hash_entry + (struct elf_link_hash_entry **, unsigned int, Elf_Internal_Shdr *); + /* Large common section. */ extern asection _bfd_elf_large_com_section; Index: binutils-2.38/bfd/elf64-x86-64.c =================================================================== --- binutils-2.38.orig/bfd/elf64-x86-64.c +++ binutils-2.38/bfd/elf64-x86-64.c @@ -1484,7 +1484,7 @@ elf_x86_64_convert_load_reloc (bfd *abfd bool to_reloc_pc32; bool abs_symbol; bool local_ref; - asection *tsec; + asection *tsec = NULL; bfd_signed_vma raddend; unsigned int opcode; unsigned int modrm; @@ -1639,6 +1639,9 @@ elf_x86_64_convert_load_reloc (bfd *abfd return true; } + if (tsec == NULL) + return false; + /* Don't convert GOTPCREL relocation against large section. */ if (elf_section_data (tsec) != NULL && (elf_section_flags (tsec) & SHF_X86_64_LARGE) != 0) @@ -1915,10 +1918,7 @@ elf_x86_64_scan_relocs (bfd *abfd, struc else { isym = NULL; - h = sym_hashes[r_symndx - symtab_hdr->sh_info]; - while (h->root.type == bfd_link_hash_indirect - || h->root.type == bfd_link_hash_warning) - h = (struct elf_link_hash_entry *) h->root.u.i.link; + h = _bfd_elf_get_link_hash_entry (sym_hashes, r_symndx, symtab_hdr); } /* Check invalid x32 relocations. */ Index: binutils-2.38/bfd/elflink.c =================================================================== --- binutils-2.38.orig/bfd/elflink.c +++ binutils-2.38/bfd/elflink.c @@ -62,6 +62,27 @@ struct elf_find_verdep_info static bool _bfd_elf_fix_symbol_flags (struct elf_link_hash_entry *, struct elf_info_failed *); +struct elf_link_hash_entry * +_bfd_elf_get_link_hash_entry (struct elf_link_hash_entry ** sym_hashes, + unsigned int symndx, + Elf_Internal_Shdr * symtab_hdr) +{ + if (symndx < symtab_hdr->sh_info) + return NULL; + + struct elf_link_hash_entry *h = sym_hashes[symndx - symtab_hdr->sh_info]; + + /* The hash might be empty. See PR 32641 for an example of this. */ + if (h == NULL) + return NULL; + + while (h->root.type == bfd_link_hash_indirect + || h->root.type == bfd_link_hash_warning) + h = (struct elf_link_hash_entry *) h->root.u.i.link; + + return h; +} + static struct elf_link_hash_entry * get_ext_sym_hash (struct elf_reloc_cookie *cookie, unsigned long r_symndx) { @@ -75,6 +96,9 @@ get_ext_sym_hash (struct elf_reloc_cooki h = cookie->sym_hashes[r_symndx - cookie->extsymoff]; + if (h == NULL) + return NULL; + while (h->root.type == bfd_link_hash_indirect || h->root.type == bfd_link_hash_warning) h = (struct elf_link_hash_entry *) h->root.u.i.link; Index: binutils-2.38/bfd/elfxx-x86.c =================================================================== --- binutils-2.38.orig/bfd/elfxx-x86.c +++ binutils-2.38/bfd/elfxx-x86.c @@ -973,15 +973,7 @@ _bfd_x86_elf_check_relocs (bfd *abfd, goto error_return; } - if (r_symndx < symtab_hdr->sh_info) - h = NULL; - else - { - h = sym_hashes[r_symndx - symtab_hdr->sh_info]; - while (h->root.type == bfd_link_hash_indirect - || h->root.type == bfd_link_hash_warning) - h = (struct elf_link_hash_entry *) h->root.u.i.link; - } + h = _bfd_elf_get_link_hash_entry (sym_hashes, r_symndx, symtab_hdr); if (X86_NEED_DYNAMIC_RELOC_TYPE_P (is_x86_64, r_type) && NEED_DYNAMIC_RELOCATION_P (is_x86_64, info, true, h, sec, @@ -1200,10 +1192,12 @@ _bfd_x86_elf_link_relax_section (bfd *ab else { /* Get H and SEC for GENERATE_DYNAMIC_RELOCATION_P below. */ - h = sym_hashes[r_symndx - symtab_hdr->sh_info]; - while (h->root.type == bfd_link_hash_indirect - || h->root.type == bfd_link_hash_warning) - h = (struct elf_link_hash_entry *) h->root.u.i.link; + h = _bfd_elf_get_link_hash_entry (sym_hashes, r_symndx, symtab_hdr); + if (h == NULL) + { + /* FIXMEL: Issue an error message ? */ + continue; + } if (h->root.type == bfd_link_hash_defined || h->root.type == bfd_link_hash_defweak)