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Re: [RFA/Darwin v2] Avoid a crash when working on OSO without symbol.
- From: Simon Marchi <simon dot marchi at ericsson dot com>
- To: Xavier Roirand <roirand at adacore dot com>, <gdb-patches at sourceware dot org>
- Cc: <brobecker at adacore dot com>, Tristan Gingold <gingold at adacore dot com>, <tgingold at free dot fr>
- Date: Thu, 8 Mar 2018 17:51:23 -0500
- Subject: Re: [RFA/Darwin v2] Avoid a crash when working on OSO without symbol.
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On 2018-03-01 06:38 AM, Xavier Roirand wrote:
> From: Tristan Gingold <gingold@adacore.com>
>
> When reading OSO file without symbol, macho_add_oso_symfile
> may crash when creating empty hash table.
>
> This patch fix this.
>
> gdb/ChangeLog: (Tristan Gingold <gingold@adacore.com>)
>
> * machoread.c (macho_add_oso_symfile): Handle case
> when OSO does not have symbol.
> ---
> gdb/ChangeLog | 6 ++++++
> gdb/machoread.c | 5 +++++
> 2 files changed, 11 insertions(+)
>
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index 59265157b4..050376a696 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,9 @@
> +2018-02-27 Tristan Gingold <gingold@adacore.com>
> +
> + Pushed by Xavier Roirand <roirand@adacore.com>
> + * machoread.c (macho_add_oso_symfile): Handle case when
> + OSO does not have symbol.
> +
> 2018-02-28 Sergio Durigan Junior <sergiodj@redhat.com>
> Simon Marchi <simon.marchi@polymtl.ca>
>
> diff --git a/gdb/machoread.c b/gdb/machoread.c
> index b270675d61..b00ef133a9 100644
> --- a/gdb/machoread.c
> +++ b/gdb/machoread.c
> @@ -579,6 +579,11 @@ macho_add_oso_symfile (oso_el *oso, const gdb_bfd_ref_ptr &abfd,
> {
> struct macho_sym_hash_entry *ent;
>
> + /* Nothing to do if there is no symbol (and avoid a crash
> + while creating an empty hash table). */
> + if (oso->nbr_syms == 0)
> + continue;
> +
> ent = (struct macho_sym_hash_entry *)
> bfd_hash_lookup (&table, sym->name, FALSE, FALSE);
> if (ent != NULL)
>
Hi Xavier and Tristan,
If you are able to reproduce the crash yourself, could you give just
a bit more details? I have no context, but I don't think it should
be a problem to do a lookup on an empty hash table (it shouldn't crash).
Maybe the problem is that we call bfd_hash_table_init_n with size == 0,
which puts the table in a wrong state and makes further lookups crash?
If so, I think it would better to fix the call to bfd_hash_table_init_n
to avoid passing 0. Otherwise, bfd_hash_table_init_n could check for
size == 0 (and use size = 1 instead in that case), but that would
have to be contributed to the BFD project (on the binutils mailing list).
Simon