From e2f0094c315746ff15b8d9650cf318f81d8416d7 Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@smart-cactus.org>
Date: Tue, 19 Jul 2022 01:35:40 -0400
Subject: rts/ProfHeap: Ensure new Censuses are zeroed

When growing the Census array ProfHeap previously neglected to
zero the new part of the array. Consequently `freeEra` would attempt to
free random words that often looked suspiciously like pointers.

Fixes #21880.
---
 rts/ProfHeap.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rts/ProfHeap.c b/rts/ProfHeap.c
index 0e3848d616..d9e66d76d1 100644
--- a/rts/ProfHeap.c
+++ b/rts/ProfHeap.c
@@ -377,6 +377,7 @@ nextEra( void )
             n_censuses *= 2;
             censuses = stgReallocBytes(censuses, sizeof(Census) * n_censuses,
                                        "nextEra");
+            memset(&censuses[era], 0, sizeof(Census) * n_censuses / 2);
         }
     }
 #endif /* PROFILING */
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