[PATCH] Remove MAX_REGISTER_SIZE from py-unwind.c
Alan Hayward
Alan.Hayward@arm.com
Thu Jun 22 14:36:00 GMT 2017
> On 22 Jun 2017, at 14:22, Pedro Alves <palves@redhat.com> wrote:
>
> On 06/22/2017 02:13 PM, Alan Hayward wrote:
>
>> Ok, pushed with changes as suggested.
>>
>> Patch below.
>
> Sorry, but this looks broken to me.
>
> cached_frame_info is using the trailing array idiom ...
>
>> @@ -93,7 +84,7 @@ typedef struct
>> /* Length of the `reg' array below. */
>> int reg_count;
>>
>> - struct reg_info reg[];
>> + cached_reg_t reg[];
>> } cached_frame_info;
>>
>
>>
>> - cached_frame
>> - = ((cached_frame_info *)
>> - xmalloc (sizeof (*cached_frame)
>> - + reg_count * sizeof (cached_frame->reg[0])));
>> + cached_frame = XNEW (cached_frame_info);
>
> but now you're not allocating enough space for the array elements...
>
>
>> cached_frame->gdbarch = gdbarch;
>> cached_frame->frame_id = unwind_info->frame_id;
>> cached_frame->reg_count = reg_count;
>> @@ -580,13 +568,14 @@ pyuw_sniffer (const struct frame_unwind *self, struct frame_info *this_frame,
>> struct value *value = value_object_to_value (reg->value);
>> size_t data_size = register_size (gdbarch, reg->number);
>>
>> - cached_frame->reg[i].number = reg->number;
>> + cached_frame->reg[i].num = reg->number;
>
> ... that you're accessing here and below.
>
> Valgrind probably shows the now-out-of-bounds accesses.
>
>
Ouch! My mistake.
Quick patch to revert that line to it’s previous state.
Ok?
2017-06-22 Alan Hayward <alan.hayward@arm.com>
* python/py-unwind.c (pyuw_sniffer): Allocate space for
registers.
diff --git a/gdb/python/py-unwind.c b/gdb/python/py-unwind.c
index da1703ecf2b843d9a6790f095e64c2915280ae35..1d800a7b7861da6a168440b600fb2862c42b4e4b 100644
--- a/gdb/python/py-unwind.c
+++ b/gdb/python/py-unwind.c
@@ -557,7 +557,10 @@ pyuw_sniffer (const struct frame_unwind *self, struct frame_info *this_frame,
saved_reg *reg;
int i;
- cached_frame = XNEW (cached_frame_info);
+ cached_frame
+ = ((cached_frame_info *)
+ xmalloc (sizeof (*cached_frame)
+ + reg_count * sizeof (cached_frame->reg[0])));
cached_frame->gdbarch = gdbarch;
cached_frame->frame_id = unwind_info->frame_id;
cached_frame->reg_count = reg_count;
More information about the Gdb-patches
mailing list