[Crash-utility] [PATCH v4 4/4] Add check if an syment element is installed one more time

[lijiang]

> Date: Sat, 18 Sep 2021 15:59:32 +0800
> From: Tao Liu <ltao at redhat.com>
> To: crash-utility at redhat.com
> Subject: [Crash-utility] [PATCH v4 4/4] Add check if an syment element
>         is      installed one more time
> Message-ID: <20210918075932.132339-5-ltao at redhat.com>
> Content-Type: text/plain; charset="US-ASCII"
>
> symname_hash_install won't check if spn has been installed before. If
> it does, the second install will corrupt the hash table as well as
> spn->cnt counting. This patch adds the check to avoid such risks.
>
> Signed-off-by: Tao Liu <ltao at redhat.com>
> ---
>  symbols.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/symbols.c b/symbols.c
> index f7157b1..6d12c55 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -1147,6 +1147,20 @@ mod_symtable_hash_remove_range(struct syment *from, struct syment *to)
>                 symname_hash_remove(st->mod_symname_hash, sp);
>  }
>
> +static inline int
> +syment_is_installed(struct syment *table[], struct syment *spn)
> +{
> +       struct syment *sp;
> +       int index;
> +
> +       index = SYMNAME_HASH_INDEX(spn->name);
> +       for (sp = table[index]; sp; sp = sp->name_hash_next) {
> +               if (sp == spn)
> +                       return TRUE;
> +       }
> +       return FALSE;
> +}
> +
>  /*
>   *  Install a single static kernel symbol into the symname_hash.
>   */
> @@ -1156,7 +1170,7 @@ symname_hash_install(struct syment *table[], struct syment *spn)
>         struct syment *sp;
>          int index;
>
> -       if (!spn)
> +       if (!spn || syment_is_installed(table, spn))
>                 return;

Here, why don't we call the existing symname_hash_search() and
redefine a new syment_is_installed()? Could you please describe more
details?

Thanks.
Lianbo

>
>          index = SYMNAME_HASH_INDEX(spn->name);
> --
> 2.29.2