From 8fdd277fe6ee1770b12650a4bc2bc257e49c8065 Mon Sep 17 00:00:00 2001
From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Tue, 10 May 2022 15:09:12 +0000
Subject: [PATCH] runtime: profile finalizer G more carefully in goroutine
 profile

If SetFinalizer is never called, we might readgstatus on a nil fing
variable, resulting in a crash. This change guards code that accesses
fing by a nil check.

Fixes #52821.

Change-Id: I3e8e7004f97f073dc622e801a1d37003ea153a29
Reviewed-on: https://go-review.googlesource.com/c/go/+/405475
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Rhys Hiltner <rhys@justin.tv>
---
 src/runtime/mprof.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/runtime/mprof.go b/src/runtime/mprof.go
index cd63bafebb..2046e9f245 100644
--- a/src/runtime/mprof.go
+++ b/src/runtime/mprof.go
@@ -952,9 +952,9 @@ func goroutineProfileWithLabelsConcurrent(p []StackRecord, labels []unsafe.Point
 	// system goroutine (to be excluded). Pick one before restarting the world.
 	if fing != nil {
 		fing.goroutineProfiled.Store(goroutineProfileSatisfied)
-	}
-	if readgstatus(fing) != _Gdead && !isSystemGoroutine(fing, false) {
-		doRecordGoroutineProfile(fing)
+		if readgstatus(fing) != _Gdead && !isSystemGoroutine(fing, false) {
+			doRecordGoroutineProfile(fing)
+		}
 	}
 	startTheWorld()
 
-- 
2.50.0