From 28fe1d7bf89f8ed5be70b98a33932dbaf99345dd Mon Sep 17 00:00:00 2001 From: Sami Tolvanen Date: Tue, 21 Apr 2020 15:08:42 -0700 Subject: [PATCH] objtool: use gelf_getsymshndx to handle >64k sections Currently, objtool fails to load the correct section for symbols when the index is greater than SHN_LORESERVE. Use gelf_getsymshndx instead of gelf_getsym to handle >64k sections. Signed-off-by: Sami Tolvanen Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Kees Cook Link: https://lkml.kernel.org/r/20200421220843.188260-2-samitolvanen@google.com --- tools/objtool/elf.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index b6349ca..8422567 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -343,12 +343,14 @@ static int read_sections(struct elf *elf) static int read_symbols(struct elf *elf) { - struct section *symtab, *sec; + struct section *symtab, *symtab_shndx, *sec; struct symbol *sym, *pfunc; struct list_head *entry; struct rb_node *pnode; int symbols_nr, i; char *coldstr; + Elf_Data *shndx_data = NULL; + Elf32_Word shndx; symtab = find_section_by_name(elf, ".symtab"); if (!symtab) { @@ -356,6 +358,10 @@ static int read_symbols(struct elf *elf) return -1; } + symtab_shndx = find_section_by_name(elf, ".symtab_shndx"); + if (symtab_shndx) + shndx_data = symtab_shndx->data; + symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize; for (i = 0; i < symbols_nr; i++) { @@ -369,8 +375,9 @@ static int read_symbols(struct elf *elf) sym->idx = i; - if (!gelf_getsym(symtab->data, i, &sym->sym)) { - WARN_ELF("gelf_getsym"); + if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym, + &shndx)) { + WARN_ELF("gelf_getsymshndx"); goto err; } @@ -384,10 +391,13 @@ static int read_symbols(struct elf *elf) sym->type = GELF_ST_TYPE(sym->sym.st_info); sym->bind = GELF_ST_BIND(sym->sym.st_info); - if (sym->sym.st_shndx > SHN_UNDEF && - sym->sym.st_shndx < SHN_LORESERVE) { - sym->sec = find_section_by_index(elf, - sym->sym.st_shndx); + if ((sym->sym.st_shndx > SHN_UNDEF && + sym->sym.st_shndx < SHN_LORESERVE) || + (shndx_data && sym->sym.st_shndx == SHN_XINDEX)) { + if (sym->sym.st_shndx != SHN_XINDEX) + shndx = sym->sym.st_shndx; + + sym->sec = find_section_by_index(elf, shndx); if (!sym->sec) { WARN("couldn't find section for symbol %s", sym->name); -- 2.7.4