Message-Id: <200406092040.i59KeMaC028141@turing-police.cc.vt.edu>
To: arjanv@redhat.com
Cc: Pekka Enberg <penberg@cs.helsinki.fi>, Chris Wright <chrisw@osdl.org>,
       linux-kernel@vger.kernel.org, tiwai@suse.de
Subject: Re: [PATCH] ALSA: Remove subsystem-specific malloc (1/8) 
In-Reply-To: Your message of "Wed, 09 Jun 2004 22:21:26 +0200."
             <1086812486.2810.21.camel@laptop.fenrus.com> 
From: Valdis.Kletnieks@vt.edu
References: <200406082124.i58LOuOL016163@melkki.cs.helsinki.fi> <20040609113455.U22989@build.pdx.osdl.net> <1086812001.13026.63.camel@cherry>
            <1086812486.2810.21.camel@laptop.fenrus.com>
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On Wed, 09 Jun 2004 22:21:26 +0200, Arjan van de Ven said:

> > + */
> > +void *kcalloc(size_t n, size_t size, int flags)
> > +{
> > +	void *ret = kmalloc(n * size, flags);
> 
> how about making sure n*size doesn't overflow an int in this function?
> We had a few security holes due to that happening a while ago; might as
> well prevent it from happening entirely

Do we want 'int', or is some other value (size_t? u32?) a better bet? (I see on
some of the 64-bit boxes a compat_size_t for 32-bits as well, which hints at
the problems here....

I'm worried that 'int' will Do The Wrong Thing when it runs into stuff like
this from asm-i386/types.h:

/* DMA addresses come in generic and 64-bit flavours.  */

#ifdef CONFIG_HIGHMEM64G
typedef u64 dma_addr_t;
#else
typedef u32 dma_addr_t;
#endif
typedef u64 dma64_addr_t;

Are there any platforms where 'int' and 'max reasonable kmalloc size' have the
same number of bits?

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