* [patch] fix for crash in python pretty-printer
@ 2009-07-07 18:01 Paul Pluzhnikov
2009-07-07 18:23 ` Tom Tromey
0 siblings, 1 reply; 6+ messages in thread
From: Paul Pluzhnikov @ 2009-07-07 18:01 UTC (permalink / raw)
To: gdb-patches; +Cc: ppluzhnikov, archer
Greetings,
This is rather on the obvious side.
While debugging a buggy pretty-printer, GDB crashed on me:
Program received signal SIGSEGV, Segmentation fault.
0x000000000045db13 in do_my_cleanups (pmy_chain=0xa7c020, old_chain=0x1e65a10) at ../../gdb/utils.c:390
390 *pmy_chain = ptr->next; /* Do this first incase recursion */
ptr is NULL at that point.
(top) bt
#0 0x000000000045db13 in do_my_cleanups (pmy_chain=0xa7c020, old_chain=0x1e65a10) at ../../gdb/utils.c:390
#1 0x000000000045dadf in do_cleanups (...) at ../../gdb/utils.c:374
#2 0x00000000004d684b in apply_val_pretty_printer (...) at ../../gdb/python/python-prettyprint.c:526
#3 0x000000000051286a in value_print (...) at ../../gdb/valprint.c:388
#4 0x0000000000514f53 in print_formatted (...) at ../../gdb/printcmd.c:316
...
Attached is a fix (applies both to mainline and archer-tromey-python).
Tested on Linux/x86_64 with no regressions.
P.S. Is there an "easy" way to find such mis-uses of TRY_CATCH?
This one took me 2 hours to find :-(
Thanks,
--
Paul Pluzhnikov
2009-07-07 Paul Pluzhnikov <ppluzhnikov@google.com>
* python/python-value.c (valpy_getitem): Don't return from TRY_CATCH.
diff --git a/gdb/python/python-value.c b/gdb/python/python-value.c
index 8c85ef6..489b65b 100644
--- a/gdb/python/python-value.c
+++ b/gdb/python/python-value.c
@@ -290,8 +290,7 @@ valpy_getitem (PyObject *self, PyObject *key)
{
value_object *self_value = (value_object *) self;
char *field = NULL;
- struct value *idx = NULL;
- struct value *res_val = NULL; /* Initialize to appease gcc warning. */
+ struct value *res_val = NULL;
volatile struct gdb_exception except;
if (gdbpy_is_string (key))
@@ -313,12 +312,17 @@ valpy_getitem (PyObject *self, PyObject *key)
value code throw an exception if the index has an invalid
type. */
struct value *idx = convert_value_from_python (key);
- if (idx == NULL)
- return NULL;
-
- res_val = value_subscript (tmp, value_as_long (idx));
+ if (idx != NULL)
+ res_val = value_subscript (tmp, value_as_long (idx));
}
}
+
+ if (res_val == NULL)
+ {
+ gdb_assert (field == NULL);
+ return NULL;
+ }
+
if (field)
xfree (field);
GDB_PY_HANDLE_EXCEPTION (except);
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] fix for crash in python pretty-printer
2009-07-07 18:01 [patch] fix for crash in python pretty-printer Paul Pluzhnikov
@ 2009-07-07 18:23 ` Tom Tromey
2009-07-07 19:51 ` Paul Pluzhnikov
0 siblings, 1 reply; 6+ messages in thread
From: Tom Tromey @ 2009-07-07 18:23 UTC (permalink / raw)
To: Paul Pluzhnikov; +Cc: gdb-patches, archer
>>>>> "Paul" == Paul Pluzhnikov <ppluzhnikov@google.com> writes:
Paul> Attached is a fix (applies both to mainline and archer-tromey-python).
Paul> Tested on Linux/x86_64 with no regressions.
This is ok. Thanks.
Paul> P.S. Is there an "easy" way to find such mis-uses of TRY_CATCH?
Paul> This one took me 2 hours to find :-(
Not that I know of :(
You could try coccinelle, I suppose. I've run it for other purposes
on gdb, though with mixed results.
Tom
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] fix for crash in python pretty-printer
2009-07-07 18:23 ` Tom Tromey
@ 2009-07-07 19:51 ` Paul Pluzhnikov
2009-07-07 20:41 ` Paul Pluzhnikov
0 siblings, 1 reply; 6+ messages in thread
From: Paul Pluzhnikov @ 2009-07-07 19:51 UTC (permalink / raw)
To: Tom Tromey; +Cc: gdb-patches, archer
On Tue, Jul 7, 2009 at 11:23 AM, Tom Tromey<tromey@redhat.com> wrote:
> This is ok. Thanks.
Committed to the mainline.
> You could try coccinelle, I suppose. I've run it for other purposes
> on gdb, though with mixed results.
For reference, here is an intro: http://lwn.net/Articles/315686/
Thanks,
--
Paul Pluzhnikov
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] fix for crash in python pretty-printer
2009-07-07 19:51 ` Paul Pluzhnikov
@ 2009-07-07 20:41 ` Paul Pluzhnikov
2009-07-07 20:54 ` Tom Tromey
0 siblings, 1 reply; 6+ messages in thread
From: Paul Pluzhnikov @ 2009-07-07 20:41 UTC (permalink / raw)
To: Tom Tromey; +Cc: gdb-patches, archer
[-- Attachment #1: Type: text/plain, Size: 484 bytes --]
On Tue, Jul 7, 2009 at 12:50 PM, Paul Pluzhnikov<ppluzhnikov@google.com> wrote:
> Committed to the mainline.
It turns out I didn't follow what happens when value_struct_elt() raises
error correctly: when it does, res_val will be left as NULL, and that will
trigger gdb_assert in my previous patch.
Here is a fix. Sorry for the noise :-(
--
Paul Pluzhnikov
2009-07-07 Paul Pluzhnikov <ppluzhnikov@google.com>
* python/python-value.c (valpy_getitem): Remove incorrect assert.
[-- Attachment #2: gdb-pretty-printer-crash-20090707-2.txt --]
[-- Type: text/plain, Size: 682 bytes --]
Index: python/python-value.c
===================================================================
RCS file: /cvs/src/src/gdb/python/python-value.c,v
retrieving revision 1.22
diff -u -p -u -r1.22 python-value.c
--- python/python-value.c 7 Jul 2009 19:36:09 -0000 1.22
+++ python/python-value.c 7 Jul 2009 20:32:27 -0000
@@ -294,17 +294,11 @@ valpy_getitem (PyObject *self, PyObject
}
}
- if (res_val == NULL)
- {
- gdb_assert (field == NULL);
- return NULL;
- }
-
if (field)
xfree (field);
GDB_PY_HANDLE_EXCEPTION (except);
- return value_to_value_object (res_val);
+ return res_val ? value_to_value_object (res_val) : NULL;
}
static int
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] fix for crash in python pretty-printer
2009-07-07 20:41 ` Paul Pluzhnikov
@ 2009-07-07 20:54 ` Tom Tromey
2009-07-07 21:05 ` Paul Pluzhnikov
0 siblings, 1 reply; 6+ messages in thread
From: Tom Tromey @ 2009-07-07 20:54 UTC (permalink / raw)
To: Paul Pluzhnikov; +Cc: gdb-patches, archer
>>>>> "Paul" == Paul Pluzhnikov <ppluzhnikov@google.com> writes:
Paul> It turns out I didn't follow what happens when value_struct_elt() raises
Paul> error correctly: when it does, res_val will be left as NULL, and that will
Paul> trigger gdb_assert in my previous patch.
I missed that too.
Paul> Here is a fix. Sorry for the noise :-(
No big deal. This is ok if you haven't committed it already.
Paul> if (field)
Paul> xfree (field);
Jim Meyering has been going around removing these redundant 'if's.
This is something I'm *sure* coccinelle can do :-)
BTW, I neglected to mention upthread -- Taras has got dehydra and
treehydra working for C. So, you could probably write a TRY_CATCH
checker in javascript without too much trouble.
Tom
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] fix for crash in python pretty-printer
2009-07-07 20:54 ` Tom Tromey
@ 2009-07-07 21:05 ` Paul Pluzhnikov
0 siblings, 0 replies; 6+ messages in thread
From: Paul Pluzhnikov @ 2009-07-07 21:05 UTC (permalink / raw)
To: Tom Tromey; +Cc: gdb-patches, archer
On Tue, Jul 7, 2009 at 1:54 PM, Tom Tromey<tromey@redhat.com> wrote:
> This is ok if you haven't committed it already.
Thanks, now committed.
> Jim Meyering has been going around removing these redundant 'if's.
I killed that one :)
--
Paul Pluzhnikov
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2009-07-07 21:05 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2009-07-07 18:01 [patch] fix for crash in python pretty-printer Paul Pluzhnikov
2009-07-07 18:23 ` Tom Tromey
2009-07-07 19:51 ` Paul Pluzhnikov
2009-07-07 20:41 ` Paul Pluzhnikov
2009-07-07 20:54 ` Tom Tromey
2009-07-07 21:05 ` Paul Pluzhnikov
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