linux-kernel - [PATCH] idr: prevent NULL deref on lookups before insertions

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Date:	Wed, 20 Feb 2013 13:44:13 -0500
From:	Sasha Levin <sasha.levin@...cle.com>
To:	tj@...nel.org
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Sasha Levin <sasha.levin@...cle.com>
Subject: [PATCH] idr: prevent NULL deref on lookups before insertions

'hint' will be NULL if we're looking up before adding anything
to the IDR.

Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---
 include/linux/idr.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/idr.h b/include/linux/idr.h
index aed2a0c..a6f38b5 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -113,7 +113,7 @@ static inline void *idr_find(struct idr *idr, int id)
 {
 	struct idr_layer *hint = rcu_dereference_raw(idr->hint);
 
-	if ((id & ~IDR_MASK) == hint->prefix)
+	if (hint && (id & ~IDR_MASK) == hint->prefix)
 		return rcu_dereference_raw(hint->ary[id & IDR_MASK]);
 
 	return idr_find_slowpath(idr, id);
-- 
1.8.1.2

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