Re: BUG #19458: OOM killer in jsonb_path_exists_opr (@?) with malformed JSONPath containing non-existent variables - Mailing list pgsql-bugs
| From | Andrey Rachitskiy |
|---|---|
| Subject | Re: BUG #19458: OOM killer in jsonb_path_exists_opr (@?) with malformed JSONPath containing non-existent variables |
| Date | |
| Msg-id | CAB8bMit1HvJsAasUYwmq+82Oa3zQhJyvsHNS4PGF_S_BCMnuVA@mail.gmail.com Whole thread |
| In response to | BUG #19458: OOM killer in jsonb_path_exists_opr (@?) with malformed JSONPath containing non-existent variables (PG Bug reporting form <noreply@postgresql.org>) |
| List | pgsql-bugs |
I propose a targeted backpatch for REL_14/15/16 in jsonpath_exec.c to align missing variable handling with newer branches and prevent pathological memory growth on malformed/hostile jsonpath expressions.
Why this is not a full backport
This is intentionally not a full backport of the REL_17 jsonpath executor refactoring (callbacks for variable access, broader executor integration, etc.).
Why this still fixes the reported issue
On REL_14/15/16, with current behavior (missing vars -> null), some crafted jsonpath expressions continue deep evaluation and can consume very large memory, leading to OOM.
With this patch, execution fails early on undefined variable, matching REL_17 behavior for this case and avoiding runaway memory use.
—
Regards,
Andrey Rachitskiy
Postgres Professional
Why this is not a full backport
This is intentionally not a full backport of the REL_17 jsonpath executor refactoring (callbacks for variable access, broader executor integration, etc.).
Why this still fixes the reported issue
On REL_14/15/16, with current behavior (missing vars -> null), some crafted jsonpath expressions continue deep evaluation and can consume very large memory, leading to OOM.
With this patch, execution fails early on undefined variable, matching REL_17 behavior for this case and avoiding runaway memory use.
—
Regards,
Andrey Rachitskiy
Postgres Professional
пт, 17 апр. 2026 г. в 16:21, PG Bug reporting form <noreply@postgresql.org>:
The following bug has been logged on the website:
Bug reference: 19458
Logged by: Andrey Rachitskiy
Email address: pl0h0yp1@gmail.com
PostgreSQL version: 14.22
Operating system: Debian GNU/Linux 12 (bookworm)
Description:
Description:
During fuzzing of the jsonb_path_exists_opr (operator jsonb @? jsonpath, a
two-argument version of jsonb_path_exists()), a pathological query was
discovered that causes uncontrolled memory consumption, leading to OOM
Killer on PostgreSQL versions REL_14/15/16_STABLE.
On versions 17 and 18, the same query returns a proper error instead of
crashing the server.
This bug was found using AFL++ as a fuzzer and LibBlobStamper as a tool for
creating syntactically correct arguments.
Reproduction:
Execute the following query:
```sql
select '[3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
13558284848669739, 3472328296227668016, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328295419228208, 3472328296227680304,
3528904766546522246, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296328343600,
3472328296227680304, 3472328296227680299, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3470920921344127024, 3906362710315511856,
3472328296228075062, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472334893297446960, 3472328090069248816,
13511005849006128, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
3472328296227680304, 3472328296227680304, 3472328296227680304,
13563782407139376, 4337019423877509168]'::jsonb @? '(-$?(0 <
($"〰〭〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰" - $?(0 < $"〰〰〰〰〰〰〰〰〰〰〰〰〰〰" - $?(0 + $ <
$"㘰〰㘶〰")."〰〰〰〰")."〰〰〰〰〰〰〰〰") - 0?(+$ < $"〰
〰〰〰")."ほ〰〰㘰")."〰〰〰〶〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰")'::jsonpath;
```
Expected result:
The query should return an error, as happens on versions 17 and 18:
ERROR: could not find jsonpath variable "〰〭〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰〰"
Actual result (14, 15, 16):
- Memory consumption grows until the kernel kills the postgres process via
OOM Killer
- Client loses connection:
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
Kernel log:
516294.487767] Out of memory: Killed process 1135405 (postgres)
total-vm:13521932kB, anon-rss:9170792kB, file-rss:92kB, shmem-rss:1848kB,
UID:1002 pgtables:26176kB oom_score_adj:0
--
Regards,
Andrey Rachitskiy
Postgres Professional
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