From: Kees Cook <keescook@chromium.org>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] objtool: use gelf_getsymshndx to handle >64k sections
Date: Tue, 21 Apr 2020 13:11:47 -0700 [thread overview]
Message-ID: <202004211311.EF577DFD13@keescook> (raw)
In-Reply-To: <20200421180724.245410-2-samitolvanen@google.com>
On Tue, Apr 21, 2020 at 11:07:22AM -0700, Sami Tolvanen wrote:
> 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 <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
-Kees
> ---
> 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 09ddc8f1def3..887445e87380 100644
> --- a/tools/objtool/elf.c
> +++ b/tools/objtool/elf.c
> @@ -327,12 +327,14 @@ 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) {
> @@ -340,6 +342,10 @@ 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++) {
> @@ -353,8 +359,9 @@ 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;
> }
>
> @@ -368,10 +375,13 @@ 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);
> --
> 2.26.1.301.g55bc3eb7cb9-goog
>
--
Kees Cook
next prev parent reply other threads:[~2020-04-21 20:11 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-21 18:07 [PATCH 0/3] objtool: add support for >64k sections Sami Tolvanen
2020-04-21 18:07 ` [PATCH 1/3] objtool: use gelf_getsymshndx to handle " Sami Tolvanen
2020-04-21 20:11 ` Kees Cook [this message]
2020-04-21 18:07 ` [PATCH 2/3] objtool: optimize insn_hash for split sections Sami Tolvanen
2020-04-21 19:47 ` Peter Zijlstra
2020-04-21 20:13 ` Kees Cook
2020-04-21 20:20 ` Sami Tolvanen
2020-04-21 18:07 ` [PATCH 3/3] objtool: optimize add_dead_ends " Sami Tolvanen
2020-04-21 20:13 ` Josh Poimboeuf
2020-04-21 20:17 ` Kees Cook
2020-04-21 22:02 ` Sami Tolvanen
2020-04-21 20:14 ` Kees Cook
2020-04-21 20:11 ` [PATCH 0/3] objtool: add support for >64k sections Kees Cook
2020-04-21 22:08 ` [PATCH v2 0/2] " Sami Tolvanen
2020-04-21 22:08 ` [PATCH v2 1/2] objtool: use gelf_getsymshndx to handle " Sami Tolvanen
2020-05-15 17:22 ` [tip: objtool/core] " tip-bot2 for Sami Tolvanen
2020-04-21 22:08 ` [PATCH v2 2/2] objtool: optimize add_dead_ends for split sections Sami Tolvanen
2020-04-21 23:43 ` Kees Cook
2020-05-15 17:22 ` [tip: objtool/core] " tip-bot2 for Sami Tolvanen
2020-04-21 23:52 ` [PATCH v2 0/2] objtool: add support for >64k sections Josh Poimboeuf
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