linux-kernel - [RFC/PATCH RESEND -next 20/21] fs: dcache: manually unpoison dname after allocation to shut up kasan's reports

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Date:	Wed, 09 Jul 2014 15:30:14 +0400
From:	Andrey Ryabinin <a.ryabinin@...sung.com>
To:	linux-kernel@...r.kernel.org
Cc:	Dmitry Vyukov <dvyukov@...gle.com>,
	Konstantin Serebryany <kcc@...gle.com>,
	Alexey Preobrazhensky <preobr@...gle.com>,
	Andrey Konovalov <adech.fo@...il.com>,
	Yuri Gribov <tetra2005@...il.com>,
	Konstantin Khlebnikov <koct9i@...il.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Michal Marek <mmarek@...e.cz>,
	Russell King <linux@....linux.org.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	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>,
	linux-kbuild@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	x86@...nel.org, linux-mm@...ck.org,
	Andrey Ryabinin <a.ryabinin@...sung.com>
Subject: [RFC/PATCH RESEND -next 20/21] fs: dcache: manually unpoison dname
 after allocation to shut up kasan's reports

We need to manually unpoison rounded up allocation size for dname
to avoid kasan's reports in __d_lookup_rcu.
__d_lookup_rcu may validly read a little beyound allocated size.

Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Signed-off-by: Andrey Ryabinin <a.ryabinin@...sung.com>
---
 fs/dcache.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/dcache.c b/fs/dcache.c
index b7e8b20..dff64f2 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -38,6 +38,7 @@
 #include <linux/prefetch.h>
 #include <linux/ratelimit.h>
 #include <linux/list_lru.h>
+#include <linux/kasan.h>
 #include "internal.h"
 #include "mount.h"
 
@@ -1412,6 +1413,8 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
 			kmem_cache_free(dentry_cache, dentry); 
 			return NULL;
 		}
+		unpoison_shadow(dname,
+				roundup(name->len + 1, sizeof(unsigned long)));
 	} else  {
 		dname = dentry->d_iname;
 	}	
-- 
1.8.5.5

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