* Re: [RFA] libiberty/cplus-dem.c:demangle_template() problem?
[not found] <20031019055940.GD986@gnat.com>
@ 2003-10-20 23:27 ` Joel Brobecker
2003-10-20 23:41 ` Andrew Cagney
0 siblings, 1 reply; 4+ messages in thread
From: Joel Brobecker @ 2003-10-20 23:27 UTC (permalink / raw)
To: gdb-patches
Hello,
I just committed the following change to libiberty in the GCC tree.
Apparently, the libiberty repository is not "shared" between GCC and
GDB. This fixes a SIGSEGV that occured in GDB. Is it ok to import
this change in the GDB sources?
Thanks,
On Sat, Oct 18, 2003 at 10:59:40PM -0700, Joel Brobecker wrote:
> I noticed a SIGSEGV inside GDB while reading the symbol table.
> What GDB does with each symbol is try to compute their demangled
> name. The SEGV occured because the compiler I used (GNAT) generated
> a symbol which the demangle did not like:
>
> _test_array__L_1__B23b___clean.6
>
> GDB basically called cplus_demangle() with the above name, and kaboom!
> SIGSEGV inside work_stuff_copy_to_from().
>
> What happened is that cplus_demangle() ends up trying to demangle the
> symbol using gnu_special() which tries to see if the symbol is a
> template by calling demangle_template().
>
> The value given for parameter REMEMBER is 1, so the first thing the
> function does is registering a Btype inside the work_stuff structure.
> But as it realizes it actually is not a template, it aborts the
> execution and returns zero. However, the work->btypevec vector now
> contains a NULL entry. When the code later tries to make a copy of the
> work_stuff structure, if segfaults because it's trying to copy a NULL
> string.
>
> I think the right fix is to only register the Btype when we know we
> are going to store it. In the present case, the attached patch seemed
> to be the right fix. I also attached a patch for the testsuite. The
> testdriver segfaults before I apply my patch, and runs to completion
> after. The output is unchanged.
>
> 2003-10-19 J. Brobecker <brobecker@gnat.com>
>
> * cplus-dem.c (demangle_template): Register a new Btype only
> when needed.
> * testsuite/demangle-expected: Add a new test.
>
> OK to apply?
>
> Thanks,
> --
> Joel
Content-Description: cplus-dem.c.diff
> Index: cplus-dem.c
> ===================================================================
> RCS file: /nile.c/cvs/Dev/gdb/gdb-6.0/libiberty/cplus-dem.c,v
> retrieving revision 1.1.1.1
> diff -u -p -r1.1.1.1 cplus-dem.c
> --- cplus-dem.c 5 Oct 2003 10:40:46 -0000 1.1.1.1
> +++ cplus-dem.c 18 Oct 2003 06:42:31 -0000
> @@ -2043,13 +2043,10 @@ demangle_template (work, mangled, tname,
> const char *start;
> int is_java_array = 0;
> string temp;
> - int bindex = 0;
>
> (*mangled)++;
> if (is_type)
> {
> - if (remember)
> - bindex = register_Btype (work);
> start = *mangled;
> /* get template name */
> if (**mangled == 'z')
> @@ -2226,7 +2223,10 @@ demangle_template (work, mangled, tname,
> }
>
> if (is_type && remember)
> - remember_Btype (work, tname->b, LEN_STRING (tname), bindex);
> + {
> + const int bindex = register_Btype (work);
> + remember_Btype (work, tname->b, LEN_STRING (tname), bindex);
> + }
>
> /*
> if (work -> static_type)
> Index: demangle-expected
> ===================================================================
> RCS file: /cvs/src/src/libiberty/testsuite/demangle-expected,v
> retrieving revision 1.13
> diff -u -r1.13 demangle-expected
> --- demangle-expected 16 Oct 2003 15:22:27 -0000 1.13
> +++ demangle-expected 18 Oct 2003 19:25:46 -0000
> @@ -2864,3 +2864,9 @@
> --format=auto
> __CPR212____ct__Q3_3std141list__tm__128_Q2_3edm41THandle__tm__26_Q2_4emid15EMparticleChunkQ2_3std68allocator__tm__51_Q2_3edmJ37J14const_iteratorFRCQ3_3std18list__tm__7_Z1ZZ2Z8iterator
> __CPR212____ct__Q3_3std141list__tm__128_Q2_3edm41THandle__tm__26_Q2_4emid15EMparticleChunkQ2_3std68allocator__tm__51_Q2_3edmJ37J14const_iteratorFRCQ3_3std18list__tm__7_Z1ZZ2Z8iterator
> +#
> +# This used to cause a crash. It doesn't follow the C++ encoding so
> +# the demangled name should be identical to the original symbol name.
> +--format=auto
> +_test_array__L_1__B23b___clean.6
> +_test_array__L_1__B23b___clean.6
--
Joel
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