From 10d9dcf6ee5909e1aabd3685c60fdd1b1306d046 Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kmo@daterainc.com>
Date: Mon, 17 Feb 2014 15:48:36 -0800
Subject: bcache: Fix moving_pred()

Avoid a potential null pointer deref (e.g. from check keys for cache misses)

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
index 8c72051..5e8e587 100644
--- a/drivers/md/bcache/movinggc.c
+++ b/drivers/md/bcache/movinggc.c
@@ -24,12 +24,10 @@ static bool moving_pred(struct keybuf *buf, struct bkey *k)
 					   moving_gc_keys);
 	unsigned i;
 
-	for (i = 0; i < KEY_PTRS(k); i++) {
-		struct bucket *g = PTR_BUCKET(c, k, i);
-
-		if (GC_MOVE(g))
+	for (i = 0; i < KEY_PTRS(k); i++)
+		if (ptr_available(c, k, i) &&
+		    GC_MOVE(PTR_BUCKET(c, k, i)))
 			return true;
-	}
 
 	return false;
 }
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