linux-kernel - [PATCH] mm/sl[aou]b: make kfree() aware of error pointers

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Date:	Tue, 9 Sep 2014 23:25:28 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>
cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Dan Carpenter <dan.carpenter@...cle.com>,
	Theodore Ts'o <tytso@....edu>
Subject: [PATCH] mm/sl[aou]b: make kfree() aware of error pointers

kfree() is happy to accept NULL pointer and does nothing in such case. 
It's reasonable to expect it to behave the same if ERR_PTR is passed to 
it.

Inspired by a9cfcd63e8d ("ext4: avoid trying to kfree an ERR_PTR 
pointer").

Signed-off-by: Jiri Kosina <jkosina@...e.cz>
---
 mm/slab.c | 2 +-
 mm/slob.c | 2 +-
 mm/slub.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index a467b30..1a256ac 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3612,7 +3612,7 @@ void kfree(const void *objp)
 
 	trace_kfree(_RET_IP_, objp);
 
-	if (unlikely(ZERO_OR_NULL_PTR(objp)))
+	if (unlikely(ZERO_OR_NULL_PTR(objp) || IS_ERR(objp)))
 		return;
 	local_irq_save(flags);
 	kfree_debugcheck(objp);
diff --git a/mm/slob.c b/mm/slob.c
index 21980e0..3abc42c 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -489,7 +489,7 @@ void kfree(const void *block)
 
 	trace_kfree(_RET_IP_, block);
 
-	if (unlikely(ZERO_OR_NULL_PTR(block)))
+	if (unlikely(ZERO_OR_NULL_PTR(block) || IS_ERR(objp)))
 		return;
 	kmemleak_free(block);
 
diff --git a/mm/slub.c b/mm/slub.c
index 3e8afcc..46d18ce 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3338,7 +3338,7 @@ void kfree(const void *x)
 
 	trace_kfree(_RET_IP_, x);
 
-	if (unlikely(ZERO_OR_NULL_PTR(x)))
+	if (unlikely(ZERO_OR_NULL_PTR(x) || IS_ERR(objp)))
 		return;
 
 	page = virt_to_head_page(x);

-- 
Jiri Kosina
SUSE Labs
--
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