Correction of a crash in sim_memory_uninstall

Correction of a crash in sim_memory_uninstall

[Stephane Carrez]

Hi!

I've found a problem in the common part of the simulator.
It crashes in `sim_memory_uninstall' when the simulator terminates.

The problem is when this operation walks a list and frees the
sim_memopt objects. It frees the entry (line 457, call to zfree)
and then gets the pointer to the next one, accessing the freed data
(line 461, *entry = (*entry)->next). 

One fix consist in updating 'entry' before the while loop.

Hope this helps,

	Stephane


*** /src/gnu/gdb-19990330/sim/common/sim-memopt.c       Thu Jan 28 15:13:33
1999
--- sim-memopt.c        Sat Apr  3 20:06:42 1999
***************
*** 449,454 ****
--- 449,457 ----
  
        /* delete it and its aliases */
        alias = *entry;
+ 
+       /* next victim */
+       *entry = (*entry)->next;
        while (alias != NULL)
        {
          sim_memopt *dead = alias;
***************
*** 456,464 ****
          sim_core_detach (sd, NULL, dead->level, dead->space, dead->addr);
          zfree (dead);
        }
- 
-       /* next victim */
-       *entry = (*entry)->next;
      }
  }
  
--- 459,464 ----

Correction of a crash in sim_memory_uninstall

[Stephane Carrez]

Hi!

I've found a problem in the common part of the simulator.
It crashes in `sim_memory_uninstall' when the simulator terminates.

The problem is when this operation walks a list and frees the
sim_memopt objects. It frees the entry (line 457, call to zfree)
and then gets the pointer to the next one, accessing the freed data
(line 461, *entry = (*entry)->next). 

One fix consist in updating 'entry' before the while loop.

Hope this helps,

	Stephane


*** /src/gnu/gdb-19990330/sim/common/sim-memopt.c       Thu Jan 28 15:13:33
1999
--- sim-memopt.c        Sat Apr  3 20:06:42 1999
***************
*** 449,454 ****
--- 449,457 ----
  
        /* delete it and its aliases */
        alias = *entry;
+ 
+       /* next victim */
+       *entry = (*entry)->next;
        while (alias != NULL)
        {
          sim_memopt *dead = alias;
***************
*** 456,464 ****
          sim_core_detach (sd, NULL, dead->level, dead->space, dead->addr);
          zfree (dead);
        }
- 
-       /* next victim */
-       *entry = (*entry)->next;
      }
  }
  
--- 459,464 ----
From phdm@macqel.be Wed Apr 07 10:43:00 1999
From: "Philippe De Muyter" <phdm@macqel.be>
To: gdb-patches@cygnus.com (gdb-patches@cygnus.com)
Subject: testsuite/print_long_arg_list
Date: Wed, 07 Apr 1999 10:43:00 -0000
Message-id: <199904071649.SAA28333@mail.macqel.be>
X-SW-Source: 1999-04/msg00001.html
Content-length: 2437

Running the testsuite with gdb-4.17.87 on m68k-motorola-sysv, I got
(among others) the following failure :

print_long_arg_list (a=22.219999999999998, b=33.332999999999998, c=0, d=-25, e=1
00, f=2345, struct1={value = 6, head = 0}, struct2={value = 10, head = 0}, struc
t3={value = 12, head = 0}, struct4={value = 14, head = 0}, flags={alpha = 1, bet
a = 0, gamma = 1, delta = 0, epsilon = 1, omega = 0}, flags_combo={alpha = 1, be
ta = 0, ch1 = 121 'y', gamma = 1, delta = 0, ch2 = 110 'n', epsilon = 1, omega =
 0}, three_char={ch1 = 97 'a', ch2 = 98 'b', ch3 = 99 'c'}, five_char={ch1 = 108
 'l', ch2 = 109 'm', ch3 = 110 'n', ch4 = 111 'o', ch5 = 112 'p'}, int_char_comb
o={int1 = 123, ch1 = 122 'z'}, d1={double1 = 10.5}, d2={double1 = -3.33999999999
99998}, d3={double1 = 675.09122999999999}, f1={float1 = 45.2340012, float2 = 43.
5999985}, f2={float1 = 78.0100021, float2 = 122.099998}, f3={float1 = -1232.3449
7, float2 = -199.210007}) at call-ar-st.c:813
813         printf("double : %f\n", a);
(gdb) FAIL: gdb.base/call-ar-st.exp: step into print_long_arg_list


Looking at the expected result, I see :

    gdb_expect {
        -re ".*print_long_arg_list \\(a=22.219999999999999, b=33.332999999999998
, c=0, d=-25, e=100, f=2345, struct1=\{value = 6, head = 0\}, struct2=\{value =
10, head = 0\}, struct3=\{value = 12, head = 0\}, struct4=\{value = 14, head = 0
\}, flags=\{alpha = 1, beta = 0, gamma = 1, delta = 0, epsilon = 1, omega = 0\},
 flags_combo=\{alpha = 1, beta = 0, ch1 = 121 \'y\', gamma = 1, delta = 0, ch2 =
 110 \'n\', epsilon = 1, omega = 0\}, three_char=\{ch1 = 97 \'a\', ch2 = 98 \'b\
', ch3 = 99 \'c\'\}, five_char=\{ch1 = 108 \'l\', ch2 = 109 \'m\', ch3 = 110 \'n
\', ch4 = 111 \'o\', ch5 = 112 \'p\'\}, int_char_combo=\{int1 = 123, ch1 = 122 \
'z\'\}, d1=\{double1 = 10.5\}, d2=\{double1 = -3.3399999999999999\}, d3=\{double
1 = 675.09123\}, f1=\{float1 = 45.2340012, float2 = 43.5999985\}, f2=\{float1 =
78.0100021, float2 = 122.099998\}, f3=\{float1 = -1232.34497, float2 = -199.2100
07\}\\) at ${srcdir}/${subdir}/${srcfile}:813\[\r\n\]+813\[ \t\]+printf\\(\"doub
le :.*\", a\\);.*$gdb_prompt $" {pass "step into print_long_arg_list"}
        -re ".*$gdb_prompt $" { fail "step into print_long_arg_list" }
        timeout { fail "step into print_long_arg_list (timeout)" }
    }


For me, the differences are in the last digits of some float or double numbers.
Isn't the test too strict ?

Philippe

Re: Correction of a crash in sim_memory_uninstall

[Frank Ch. Eigler]

stcarrez@worldnet.fr (Stephane Carrez) writes:

> I've found a problem in the common part of the simulator.  It
> crashes in `sim_memory_uninstall' when the simulator terminates.
> [...]

Thanks for finding this problem.  Your patch looks fine.

- FChE
From jimb@cygnus.com Thu Apr 15 11:41:00 1999
From: Jim Blandy <jimb@cygnus.com>
To: Manfred Hollstein <manfred.h@gmx.net>
Cc: bug-gdb@gnu.org, gdb-patches@cygnus.com
Subject: Re: PATCH: fix unitialized memory reads in bfd/elf32-mips.c
Date: Thu, 15 Apr 1999 11:41:00 -0000
Message-id: <npiuaxyf3t.fsf@zwingli.cygnus.com>
References: <14034.52083.787129.934623@exept.exept.de> <14100.46517.331398.118164@saturn.hollstein.net>
X-SW-Source: 1999-04/msg00033.html
Content-length: 2716

> I reported this problem already with bfd in binutils-2.9.1 and gdb-4.17;
> as it is still present in gdb-4.18, I'm re-posting a patch.

An equivalent patch has been applied now.  Thanks!

------- Start of forwarded message -------
Message-ID: <19990414143605.B28302@cygnus.com>
Date: Wed, 14 Apr 1999 14:36:05 -0700
From: Richard Henderson <rth@cygnus.com>
To: Jim Blandy <jimb@cygnus.com>
Subject: Re: [manfred-h@t-online.de (Manfred Hollstein)] PATCH: fix unitialized memory reads in bfd/elf32-mips.c
References: <npbtgryt9k.fsf@zwingli.cygnus.com>

On Wed, Apr 14, 1999 at 01:03:03PM -0500, Jim Blandy wrote:
> 1999-04-14  Manfred Hollstein  <mhollstein@cygnus.com>
> 
> 	* elf32-mips.c (_bfd_mips_elf_read_ecoff_info): Set all
> 	fields to 0 which may cause erroneous calls to free when
> 	"goto error_return" is executed.
>
> +  debug->line = 0;
> +  debug->external_dnr = 0;
> +  debug->external_pdr = 0;
> +  debug->external_sym = 0;
> +  debug->external_opt = 0;
> +  debug->external_aux = 0;
> +  debug->ss = 0;
> +  debug->ssext = 0;
> +  debug->external_fdr = 0;
> +  debug->external_rfd = 0;
> +  debug->external_ext = 0;

I've committed the following instead.

Thanks.


r~



Wed Apr 14 14:33:08 1999  Richard Henderson  <rth@cygnus.com>

        * elf32-mips.c (_bfd_mips_elf_read_ecoff_info): Zero `debug'.
        * elf64-alpha.c (elf64_alpha_read_ecoff_info): Likewise.

Index: elf32-mips.c
===================================================================
RCS file: /cvs/cvsfiles/devo/bfd/elf32-mips.c,v
retrieving revision 1.153
diff -c -p -d -r1.153 elf32-mips.c
*** elf32-mips.c	1999/04/10 23:24:04	1.153
--- elf32-mips.c	1999/04/14 21:32:49
*************** _bfd_mips_elf_read_ecoff_info (abfd, sec
*** 3330,3335 ****
--- 3330,3336 ----
    char *ext_hdr = NULL;
  
    swap = get_elf_backend_data (abfd)->elf_backend_ecoff_debug_swap;
+   memset (debug, 0, sizeof(*debug));
  
    ext_hdr = (char *) bfd_malloc ((size_t) swap->external_hdr_size);
    if (ext_hdr == NULL && swap->external_hdr_size != 0)
Index: elf64-alpha.c
===================================================================
RCS file: /cvs/cvsfiles/devo/bfd/elf64-alpha.c,v
retrieving revision 1.43
diff -c -p -d -r1.43 elf64-alpha.c
*** elf64-alpha.c	1999/04/10 23:24:04	1.43
--- elf64-alpha.c	1999/04/14 21:32:49
*************** elf64_alpha_read_ecoff_info (abfd, secti
*** 1950,1955 ****
--- 1950,1956 ----
    char *ext_hdr = NULL;
  
    swap = get_elf_backend_data (abfd)->elf_backend_ecoff_debug_swap;
+   memset (debug, 0, sizeof(*debug));
  
    ext_hdr = (char *) bfd_malloc ((size_t) swap->external_hdr_size);
    if (ext_hdr == NULL && swap->external_hdr_size != 0)

------- End of forwarded message -------

Re: Correction of a crash in sim_memory_uninstall

[Frank Ch. Eigler]

stcarrez@worldnet.fr (Stephane Carrez) writes:

> I've found a problem in the common part of the simulator.  It
> crashes in `sim_memory_uninstall' when the simulator terminates.
> [...]

Thanks for finding this problem.  Your patch looks fine.

- FChE