puzzling JSON bug

Andrew Dunstan <andrew@dunslane.net> writes:

David Wheeler has presented me with a nasty bug case.
If I do this:

select '{"members": { "add": [3, 4]}}'::json #> '{members,add}';

then I get a crash.

If I comment out the pfree() at json.c:parse_object_field() lines 378-9
then I get back the right result but instead get a warning like this:

WARNING: problem in alloc set ExprContext: bogus aset link in block
0x1efaa80, chunk 0x1efb1f0

I'm not quite sure where I should go looking for what I've done wrong here.

Routine array-overrun memory stomp. The chunk header data for "fname"'s
alloc chunk is being overwritten here:

Watchpoint 2: *(int *) 1075253088

Old value = 1074925616
New value = -1
0x50fe14 in get_array_start (state=0x40170e88) at jsonfuncs.c:688
688 _state->array_level_index[lex_level] = -1;

It appears that lex_level is 2 but only enough room for 2 entries has
been allocated in array_level_index[].

regards, tom lane

--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers

On 04/04/2013 03:39 PM, Tom Lane wrote:

Andrew Dunstan <andrew@dunslane.net> writes:

David Wheeler has presented me with a nasty bug case.
If I do this:
select '{"members": { "add": [3, 4]}}'::json #> '{members,add}';
then I get a crash.
If I comment out the pfree() at json.c:parse_object_field() lines 378-9
then I get back the right result but instead get a warning like this:
WARNING: problem in alloc set ExprContext: bogus aset link in block
0x1efaa80, chunk 0x1efb1f0
I'm not quite sure where I should go looking for what I've done wrong here.

Routine array-overrun memory stomp. The chunk header data for "fname"'s
alloc chunk is being overwritten here:

Watchpoint 2: *(int *) 1075253088

Old value = 1074925616
New value = -1
0x50fe14 in get_array_start (state=0x40170e88) at jsonfuncs.c:688
688 _state->array_level_index[lex_level] = -1;

It appears that lex_level is 2 but only enough room for 2 entries has
been allocated in array_level_index[].

OK, many thanks, will fix.

cheers

andrew

--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers