From 4ddfbd2a8ea9b41ced0cad1d984c833085f8ce91 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 fb167f226a0..495e449a9e9 100644 --- a/src/backend/utils/adt/arrayfuncs.c +++ b/src/backend/utils/adt/arrayfuncs.c @@ -6839,7 +6839,7 @@ 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; @@ -6859,8 +6859,11 @@ 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 ce6f3a65f97..97920f38c21 100644 --- a/src/test/regress/expected/arrays.out +++ b/src/test/regress/expected/arrays.out @@ -2445,3 +2445,5 @@ 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 f774faf8568..791af5c0ce1 100644 --- a/src/test/regress/sql/arrays.sql +++ b/src/test/regress/sql/arrays.sql @@ -754,3 +754,4 @@ 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