[PATCH] nm: fix treating an ifunc symbol as a stab if '--ifunc-chars=--' is given

[H.J. Lu]

On Fri, Sep 5, 2025 at 6:38 AM Dmitry Klochkov
<dmitry.klochkov@bell-sw.com> wrote:
>
> If an ifunc symbol is processed in print_symbol(), a 'type' field of a
> 'syminfo' structure is set to any character specified by a user with an
> '--ifunc-chars' option.  But afterwards the 'type' field is used to
> check whether a symbol is a stab in print_symbol_info_{bsd,sysv}()
> functions in order to print additional stab related data.  If the 'type'
> field equals '-', a symbol is treated as a stab.  If '--ifunc-chars=--'
> is given, all ifunc symbols will be treated as stab symbols and
> uninitialized stab related fields of the 'syminfo' structure will be
> printed which can lead to segmentation fault.
>
> To fix this, check if a symbol is a stab before override the 'type'
> field.  Also, add a test case for this fix.
>
>         PR binutils/32556
>         * nm.c (extended_symbol_info): Add is_stab.
>         (print_symbol): Check if a symbol is a stab.
>         (print_symbol_info_bsd): Use info->is_stab.
>         (print_symbol_info_sysv): Use info->is_stab.
>         * testsuite/binutils-all/nm.exp: Test nm --ifunc-chars=--.

Need a test to show what it does.

> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32556
> Fixes: e6f6aa8d184 ("Add option to nm to change the characters displayed for ifunc symbols")
> Signed-off-by: Dmitry Klochkov <dmitry.klochkov@bell-sw.com>
> ---
>  binutils/nm.c                          | 10 +++++++---
>  binutils/testsuite/binutils-all/nm.exp |  9 +++++++++
>  2 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/binutils/nm.c b/binutils/nm.c
> index dce9207f44f..c3d118a93c3 100644
> --- a/binutils/nm.c
> +++ b/binutils/nm.c
> @@ -70,6 +70,7 @@ struct extended_symbol_info
>    bfd_vma ssize;
>    elf_symbol_type *elfinfo;
>    coff_symbol_type *coffinfo;
> +  bool is_stab;
>    /* FIXME: We should add more fields for Type, Line, Section.  */
>  };
>  #define SYM_VALUE(sym)       (sym->sinfo->value)
> @@ -1208,8 +1209,11 @@ print_symbol (bfd *        abfd,
>
>    bfd_get_symbol_info (abfd, sym, &syminfo);
>
> +  info.is_stab = false;
> +  if (syminfo.type == '-')
> +    info.is_stab = true;
>    /* PR 22967 - Distinguish between local and global ifunc symbols.  */
> -  if (syminfo.type == 'i'
> +  else if (syminfo.type == 'i'
>        && sym->flags & BSF_GNU_INDIRECT_FUNCTION)
>      {
>        if (ifunc_type_chars == NULL || ifunc_type_chars[0] == 0)
> @@ -1873,7 +1877,7 @@ print_symbol_info_bsd (struct extended_symbol_info *info, bfd *abfd)
>
>    printf (" %c", SYM_TYPE (info));
>
> -  if (SYM_TYPE (info) == '-')
> +  if (info->is_stab)
>      {
>        /* A stab.  */
>        printf (" ");
> @@ -1902,7 +1906,7 @@ print_symbol_info_sysv (struct extended_symbol_info *info, bfd *abfd)
>
>    printf ("|   %c  |", SYM_TYPE (info));
>
> -  if (SYM_TYPE (info) == '-')
> +  if (info->is_stab)
>      {
>        /* A stab.  */
>        printf ("%18s|  ", SYM_STAB_NAME (info));                /* (C) Type.  */
> diff --git a/binutils/testsuite/binutils-all/nm.exp b/binutils/testsuite/binutils-all/nm.exp
> index fea68bf76bc..5a7c5d614d3 100644
> --- a/binutils/testsuite/binutils-all/nm.exp
> +++ b/binutils/testsuite/binutils-all/nm.exp
> @@ -329,6 +329,15 @@ if [is_elf_format] {
>             fail "$testname (local ifunc)"
>         }
>
> +       # PR 32556
> +       # Test nm --ifunc-chars=--
> +       set got [binutils_run $NM "$NMFLAGS --ifunc-chars=-- $tmpfile"]
> +       if [regexp -- "- global_foo\n\[^-\]+- local_foo" $got] then {
> +           pass "$testname=--"
> +       } else {
> +           fail "$testname=--"
> +       }
> +
>         if { $verbose < 1 } {
>             remote_file host delete "tmpdir/ifunc.o"
>         }
> --
> 2.49.0
>


-- 
H.J.