diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2022-12-12 16:17:49 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2022-12-12 16:17:54 -0500 |
| commit | b0feda79fdf02710a6039a324299525845a4a9d4 (patch) | |
| tree | 488eb42fc75b6554156f6bd359d8e15a9fd37c32 /src/backend/utils/adt/jsonb_op.c | |
| parent | 101c37cd342a3ae134bb3e5e0abb14ae46692b56 (diff) | |
Fix jsonb subscripting to cope with toasted subscript values.
jsonb_get_element() was incautious enough to use VARDATA() and
VARSIZE() directly on an arbitrary text Datum. That of course
fails if the Datum is short-header, compressed, or out-of-line.
The typical result would be failing to match any element of a
jsonb object, though matching the wrong one seems possible as well.
setPathObject() was slightly brighter, in that it used VARDATA_ANY
and VARSIZE_ANY_EXHDR, but that only kept it out of trouble for
short-header Datums. push_path() had the same issue. This could
result in faulty subscripted insertions, though keys long enough to
cause a problem are likely rare in the wild.
Having seen these, I looked around for unsafe usages in the rest
of the adt/json* files. There are a couple of places where it's not
immediately obvious that the Datum can't be compressed or out-of-line,
so I added pg_detoast_datum_packed() to cope if it is. Also, remove
some other usages of VARDATA/VARSIZE on Datums we just extracted from
a text array. Those aren't actively broken, but they will become so
if we ever start allowing short-header array elements, which does not
seem like a terribly unreasonable thing to do. In any case they are
not great coding examples, and they could also do with comments
pointing out that we're assuming we don't need pg_detoast_datum_packed.
Per report from exe-dealer@yandex.ru. Patch by me, but thanks to
David Johnston for initial investigation. Back-patch to v14 where
jsonb subscripting was introduced.
Discussion: https://postgr.es/m/205321670615953@mail.yandex.ru
Diffstat (limited to 'src/backend/utils/adt/jsonb_op.c')
| -rw-r--r-- | src/backend/utils/adt/jsonb_op.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/src/backend/utils/adt/jsonb_op.c b/src/backend/utils/adt/jsonb_op.c index 202367e9964..27e960e5043 100644 --- a/src/backend/utils/adt/jsonb_op.c +++ b/src/backend/utils/adt/jsonb_op.c @@ -63,8 +63,9 @@ jsonb_exists_any(PG_FUNCTION_ARGS) continue; strVal.type = jbvString; - strVal.val.string.val = VARDATA(key_datums[i]); - strVal.val.string.len = VARSIZE(key_datums[i]) - VARHDRSZ; + /* We rely on the array elements not being toasted */ + strVal.val.string.val = VARDATA_ANY(key_datums[i]); + strVal.val.string.len = VARSIZE_ANY_EXHDR(key_datums[i]); if (findJsonbValueFromContainer(&jb->root, JB_FOBJECT | JB_FARRAY, @@ -95,8 +96,9 @@ jsonb_exists_all(PG_FUNCTION_ARGS) continue; strVal.type = jbvString; - strVal.val.string.val = VARDATA(key_datums[i]); - strVal.val.string.len = VARSIZE(key_datums[i]) - VARHDRSZ; + /* We rely on the array elements not being toasted */ + strVal.val.string.val = VARDATA_ANY(key_datums[i]); + strVal.val.string.len = VARSIZE_ANY_EXHDR(key_datums[i]); if (findJsonbValueFromContainer(&jb->root, JB_FOBJECT | JB_FARRAY, |