From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 25 Apr 2014 19:59:57 +0000 (-0400)
Subject: Fix off-by-one bug in LWLockRegisterTranche().
X-Git-Tag: REL9_4_BETA1~106
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4bfc5f1396b18da3a0db73e4406badc4ce793a1e;p=postgresql

Fix off-by-one bug in LWLockRegisterTranche().

Original coding failed to enlarge the array as required if
the requested tranche_id was equal to LWLockTranchesAllocated.

In passing, fix poor style of not casting the result of (re)palloc.
---

diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 36b4b8bbea..df8f9bfd89 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -350,8 +350,9 @@ CreateLWLocks(void)
 	if (LWLockTrancheArray == NULL)
 	{
 		LWLockTranchesAllocated = 16;
-		LWLockTrancheArray = MemoryContextAlloc(TopMemoryContext,
-			LWLockTranchesAllocated * sizeof(LWLockTranche *));
+		LWLockTrancheArray = (LWLockTranche **)
+			MemoryContextAlloc(TopMemoryContext,
+							   LWLockTranchesAllocated * sizeof(LWLockTranche *));
 	}
 
 	MainLWLockTranche.name = "main";
@@ -423,11 +424,12 @@ LWLockRegisterTranche(int tranche_id, LWLockTranche *tranche)
 	{
 		int		i = LWLockTranchesAllocated;
 
-		while (i < tranche_id)
+		while (i <= tranche_id)
 			i *= 2;
 
-		LWLockTrancheArray = repalloc(LWLockTrancheArray,
-									  i * sizeof(LWLockTranche *));
+		LWLockTrancheArray = (LWLockTranche **)
+			repalloc(LWLockTrancheArray,
+					 i * sizeof(LWLockTranche *));
 		LWLockTranchesAllocated = i;
 	}