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Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently |
Date: |
Fri, 29 May 2009 12:57:50 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1b3pre) Gecko/20090513 Fedora/3.0-2.3.beta2.fc11 Lightning/1.0pre Thunderbird/3.0b2 |
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.
cheers,
Gerd
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, (continued)
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, Paul Brook, 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, Glauber Costa, 2009/05/29
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, Anthony Liguori, 2009/05/29
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, malc, 2009/05/29
- 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 <=
- Re: [Qemu-devel] [PATCH] use qemu_malloc and friends consistently, malc, 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