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From: Tom Tromey <tromey@redhat.com>
To: Hui Zhu <teawater@gmail.com>
Cc: Yao Qi <yao@codesourcery.com>, gdb-patches ml <gdb-patches@sourceware.org>,        Joel Brobecker <brobecker@adacore.com>
Subject: Re: [PATCH] Fix agent code generate bug of ref
References: <CANFwon0GXGwSqOyev+te3f0DBCqG3y0ovJ+yJ-kcaWkMAJOwXw@mail.gmail.com>	<513DDE2C.9080109@codesourcery.com> <87r4jmngr5.fsf@fleche.redhat.com>	<87k3penfy3.fsf@fleche.redhat.com>	<CANFwon0UqJtN2O7poC8d0X+puqR-LCfw368qKJJs50YE_wexZA@mail.gmail.com>
Date: Tue, 12 Mar 2013 14:17:00 -0000
In-Reply-To: <CANFwon0UqJtN2O7poC8d0X+puqR-LCfw368qKJJs50YE_wexZA@mail.gmail.com>	(Hui Zhu's message of "Tue, 12 Mar 2013 10:52:56 +0800")
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>>>>> "Hui" == Hui Zhu <teawater@gmail.com> writes:

Hui> Sorry for my misunderstand in your mail.  Accord to discussion with
Hui> Yao in IRC.  I merge 2 patches together.
Hui> And I found that gdb_assert of access_memory.  It should use nbytes.

Thanks for doing this.

Hui> 2013-03-12  Yao Qi  <yao@codesourcery.com>
Hui> 	    Hui Zhu  <hui_zhu@mentor.com>
Hui> 	* dwarf2loc.c (access_memory): Change nbits to nbytes in gdb_assert.
Hui> 	(dwarf2_compile_expr_to_ax): Call access_memory in DW_OP_deref and
Hui> 	DW_OP_deref_size.

Hui> +  gdb_assert (nbytes > 0 && nbytes <= sizeof (LONGEST));

Hui> -	      default:
Hui> -		/* Note that get_DW_OP_name will never return
Hui> -		   NULL here.  */
Hui> -		error (_("Unsupported size %d in %s"),
Hui> -		       size, get_DW_OP_name (op));
Hui> -	      }

I think we need a sanity check before calling access_memory.
Otherwise, bad DWARF will be able to crash gdb.
The patch is ok with that change.

Tom