postgres.git / summary / log / commit / refs

commit    e0eaeafd66462b1a584831f35f10ec1e017c3845
Author:   Alvaro Herrera <alvherre@alvh.no-ip.org>
Date:     Fri Nov 05 15:29:35 2021 +0000
First released in: 15.0, 9.6.24, 10.19, 11.14, 12.9, 13.5, 14.1

    Avoid crash in rare case of concurrent DROP
    
    When a role being dropped contains is referenced by catalog objects that
    are concurrently also being dropped, a crash can result while trying to
    construct the string that describes the objects.  Suppress that by
    ignoring objects whose descriptions are returned as NULL.
    
    The majority of relevant codesites were already cautious about this
    already; we had just missed a couple.
    
    This is an old bug, so backpatch all the way back.
    
    Reported-by: Alexander Lakhin <exclusion@gmail.com>
    Discussion: https://postgr.es/m/17126-21887f04508cb5c8@postgresql.org


 src/backend/catalog/dependency.c  | 31 ++++++++++++++++++++-----------
 src/backend/catalog/pg_shdepend.c |  6 ++++++
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index 743d91c1a11..60977f310f8 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -905,6 +905,10 @@ reportDependentObjects(const ObjectAddresses *targetObjects,
 
 		objDesc = getObjectDescription(obj);
 
+		/* An object being dropped concurrently doesn't need to be reported */
+		if (objDesc == NULL)
+			continue;
+
 		/*
 		 * If, at any stage of the recursive search, we reached the object via
 		 * an AUTO, INTERNAL, or EXTENSION dependency, then it's okay to
@@ -928,23 +932,28 @@ reportDependentObjects(const ObjectAddresses *targetObjects,
 		{
 			char	   *otherDesc = getObjectDescription(&extra->dependee);
 
-			if (numReportedClient < MAX_REPORTED_DEPS)
+			if (otherDesc)
 			{
+				if (numReportedClient < MAX_REPORTED_DEPS)
+				{
+					/* separate entries with a newline */
+					if (clientdetail.len != 0)
+						appendStringInfoChar(&clientdetail, '\n');
+					appendStringInfo(&clientdetail, _("%s depends on %s"),
+									 objDesc, otherDesc);
+					numReportedClient++;
+				}
+				else
+					numNotReportedClient++;
 				/* separate entries with a newline */
-				if (clientdetail.len != 0)
-					appendStringInfoChar(&clientdetail, '\n');
-				appendStringInfo(&clientdetail, _("%s depends on %s"),
+				if (logdetail.len != 0)
+					appendStringInfoChar(&logdetail, '\n');
+				appendStringInfo(&logdetail, _("%s depends on %s"),
 								 objDesc, otherDesc);
-				numReportedClient++;
+				pfree(otherDesc);
 			}
 			else
 				numNotReportedClient++;
-			/* separate entries with a newline */
-			if (logdetail.len != 0)
-				appendStringInfoChar(&logdetail, '\n');
-			appendStringInfo(&logdetail, _("%s depends on %s"),
-							 objDesc, otherDesc);
-			pfree(otherDesc);
 			ok = false;
 		}
 		else
diff --git a/src/backend/catalog/pg_shdepend.c b/src/backend/catalog/pg_shdepend.c
index 02f5591afae..167b9558adb 100644
--- a/src/backend/catalog/pg_shdepend.c
+++ b/src/backend/catalog/pg_shdepend.c
@@ -1073,6 +1073,12 @@ storeObjectDescription(StringInfo descs,
 {
 	char	   *objdesc = getObjectDescription(object);
 
+	/*
+	 * An object being dropped concurrently doesn't need to be reported.
+	 */
+	if (objdesc == NULL)
+		return;
+
 	/* separate entries with a newline */
 	if (descs->len != 0)
 		appendStringInfoChar(descs, '\n');


[parent: 71aeaf245b23]