postgres.git / summary / log / commit / refs

commit    982b9b1eba8d809cd677009d15ca045cea890c69
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Mon Jan 02 21:17:00 2023 +0000
First released in: 16.0, 11.19, 12.14, 13.10, 14.7, 15.2

    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 f2bb5502b21..9175f35c6b6 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -2377,6 +2377,11 @@ 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: ef3de5557687]