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Fix trim_array() for zero-dimensional array argument.

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The code tried to access ARR_DIMS(v)[0] and ARR_LBOUND(v)[0]
whether or not those values exist.  This made the range check
on the "n" argument unstable --- it might or might not fail, and
if it did it would report garbage for the allowed upper limit.
These bogus accesses would probably annoy Valgrind, and if you
were very unlucky even lead to SIGSEGV.

Report and fix by Martin Kalcher.  Back-patch to v14 where this
function was added.

Discussion: https://postgr.es/m/baaeb413-b8a8-4656-5757-ef347e5ec11f@aboutsource.net
This commit is contained in:
Tom Lane 2022-07-31 13:43:17 -04:00
parent e90c4fc881
commit e71d4254f7
3 changed files with 9 additions and 3 deletions
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5
src/backend/utils/adt/arrayfuncs.c
View File

@ -6684,7 +6684,7 @@ trim_array(PG_FUNCTION_ARGS)
{
ArrayType *v = PG_GETARG_ARRAYTYPE_P(0);
int n = PG_GETARG_INT32(1);
int array_length = ARR_DIMS(v)[0];
int array_length = (ARR_NDIM(v) > 0) ? ARR_DIMS(v)[0] : 0;
int16 elmlen;
bool elmbyval;
char elmalign;
@ -6704,8 +6704,11 @@ trim_array(PG_FUNCTION_ARGS)
/* Set all the bounds as unprovided except the first upper bound */
memset(lowerProvided, false, sizeof(lowerProvided));
memset(upperProvided, false, sizeof(upperProvided));
if (ARR_NDIM(v) > 0)
{
upper[0] = ARR_LBOUND(v)[0] + array_length - n - 1;
upperProvided[0] = true;
}
/* Fetch the needed information about the element type */
get_typlenbyvalalign(ARR_ELEMTYPE(v), &elmlen, &elmbyval, &elmalign);

2
src/test/regress/expected/arrays.out
View File

@ -2432,3 +2432,5 @@ SELECT trim_array(ARRAY[1, 2, 3], -1); -- fail
ERROR: number of elements to trim must be between 0 and 3
SELECT trim_array(ARRAY[1, 2, 3], 10); -- fail
ERROR: number of elements to trim must be between 0 and 3
SELECT trim_array(ARRAY[]::int[], 1); -- fail
ERROR: number of elements to trim must be between 0 and 0

1
src/test/regress/sql/arrays.sql
View File

@ -737,3 +737,4 @@ FROM
SELECT trim_array(ARRAY[1, 2, 3], -1); -- fail
SELECT trim_array(ARRAY[1, 2, 3], 10); -- fail
SELECT trim_array(ARRAY[]::int[], 1); -- fail