postgres.git / summary / log / commit / refs

commit    92224e470c830e73636de20689690f28037cd019
Author:   Alvaro Herrera <alvherre@alvh.no-ip.org>
Date:     Fri Nov 05 15:29:34 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 47ad2e83da9..d138b6a0d27 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -910,6 +910,10 @@ 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
@@ -933,23 +937,28 @@ 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 a24e2cefa06..ff7a1eb8247 100644
--- a/src/backend/catalog/pg_shdepend.c
+++ b/src/backend/catalog/pg_shdepend.c
@@ -1113,6 +1113,12 @@ 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: b110af5f7c9f]