From e71d4254f710bef53fa40d0b49b5af9bad10ce40 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sun, 31 Jul 2022 13:43:17 -0400 Subject: [PATCH] Fix trim_array() for zero-dimensional array argument. 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 --- src/backend/utils/adt/arrayfuncs.c | 9 ++++++--- src/test/regress/expected/arrays.out | 2 ++ src/test/regress/sql/arrays.sql | 1 + 3 files changed, 9 insertions(+), 3 deletions(-) diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c index 660e854e93f..55ba9f73deb 100644 --- a/src/backend/utils/adt/arrayfuncs.c +++ b/src/backend/utils/adt/arrayfuncs.c @@ -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)); - upper[0] = ARR_LBOUND(v)[0] + array_length - n - 1; - upperProvided[0] = true; + 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); diff --git a/src/test/regress/expected/arrays.out b/src/test/regress/expected/arrays.out index 95481ce568a..4923cf36d65 100644 --- a/src/test/regress/expected/arrays.out +++ b/src/test/regress/expected/arrays.out @@ -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 diff --git a/src/test/regress/sql/arrays.sql b/src/test/regress/sql/arrays.sql index 3ab7f392be4..5eedc4c3ce4 100644 --- a/src/test/regress/sql/arrays.sql +++ b/src/test/regress/sql/arrays.sql @@ -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