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Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently
From: |
malc |
Subject: |
Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently |
Date: |
Fri, 29 May 2009 15:28:14 +0400 (MSD) |
On Fri, 29 May 2009, Gerd Hoffmann wrote:
> On 05/29/09 11:51, malc wrote:
> > > Having qemu_malloc(0) abort is silly. Returning NULL or returning
> > > malloc(1) are both reasonable options.
> >
> > Dereference of NULL is UB[1] and dereferencing result of malloc(1) will
> > just plain work.
>
> malloc(0) itself isn't a bug. Dereferencing the pointer is.
> Code like this:
>
> buf = qemu_malloc(len);
> memcpy(buf, src, len);
>
> will work perfectly fine when called with len=0 because it will not
> dereference buf for the len=0 case. abort() in qemu_malloc for size=0 will
> fire for no good reason.
>
> > P.S. So far the abort that went into qemu_malloc caught one usage of zero
> > allocation (once again coming from qcow2).
>
> That was a false positive.
No actually it wasn't, the code with current and previous[1] versions of
qemu_malloc wouldn't work on AIX.
[1] But would work with qemu_malloc returning NULL or result of malloc(1)
--
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- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, (continued)
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, Julian Seward, 2009/05/29
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, Gerd Hoffmann, 2009/05/29
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, David Turner, 2009/05/29
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, David Turner, 2009/05/29
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, Markus Armbruster, 2009/05/29
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, Gerd Hoffmann, 2009/05/29
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently,
malc <=
Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, jcd, 2009/05/29
Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, jcd, 2009/05/29
Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, jcd, 2009/05/29
Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, jcd, 2009/05/29