linux-kernel - Re: [RFC] fix slub krealloc()

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Message-ID: <20070723133206.2220db7e@schroedinger.engr.sgi.com>
Date:	Mon, 23 Jul 2007 13:32:06 -0700
From:	Christoph Lameter <clameter@....com>
To:	Johannes Berg <johannes@...solutions.net>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	akpm@...ux-foundation.org
Subject: Re: [RFC] fix slub krealloc()

On Wed, 18 Jul 2007 17:42:11 +0200
Johannes Berg <johannes@...solutions.net> wrote:

> Commit ef2ad80c7d255ed0449eda947c2d700635b7e0f5 breaks
> krealloc(NULL, ...) badly, it BUG_ON()s.
> 
> This patch fixes it but the fix should probably be in mm/util.c
> because the documentation says that krealloc(NULL, x, gfp) is
> equivalent to kmalloc(x, gfp) and that's not true any more even after
> this patch when you do krealloc(NULL, 0, gfp)

Right. We need to fix util.c. ksize should not be called with a NULL
parameter.
Index: linux-2.6/mm/util.c
===================================================================
--- linux-2.6.orig/mm/util.c	2007-07-23 13:29:42.000000000 -0700
+++ linux-2.6/mm/util.c	2007-07-23 13:31:28.000000000 -0700
@@ -88,7 +88,11 @@ void *krealloc(const void *p, size_t new
 		return ZERO_SIZE_PTR;
 	}
 
-	ks = ksize(p);
+	if (p)
+		ks = ksize(p);
+	else
+		ks = 0;
+
 	if (ks >= new_size)
 		return (void *)p;
 
-
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