postgres.git / summary / log / commit / refs

commit    a02740e53fb7d1668e2d0ea1362743d23211d43d
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Mon Jan 02 21:17:00 2023 +0000

    Avoid reference to nonexistent array element in ExecInitAgg().
    
    When considering an empty grouping set, we fetched
    phasedata->eqfunctions[-1].  Because the eqfunctions array is
    palloc'd, that would always be an aset pointer in released versions,
    and thus the code accidentally failed to malfunction (since it would
    do nothing unless it found a null pointer).  Nonetheless this seems
    like trouble waiting to happen, so add a check for length == 0.
    
    It's depressing that our valgrind testing did not catch this.
    Maybe we should reconsider the choice to not mark that word NOACCESS?
    
    Richard Guo
    
    Discussion: https://postgr.es/m/CAMbWs4-vZuuPOZsKOYnSAaPYGKhmacxhki+vpOKk0O7rymccXQ@mail.gmail.com


 src/backend/executor/nodeAgg.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 31609c60fc6..1fdfbd1eea7 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -3574,6 +3574,11 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 				{
 					int			length = phasedata->gset_lengths[i];
 
+					/* nothing to do for empty grouping set */
+					if (length == 0)
+						continue;
+
+					/* if we already had one of this length, it'll do */
 					if (phasedata->eqfunctions[length - 1] != NULL)
 						continue;
 


[parent: fdaba0a2d749]