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Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends
From: |
Jamie Lokier |
Subject: |
Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends |
Date: |
Sun, 6 Dec 2009 18:31:57 +0000 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Ian Molton wrote:
> > Read the beginning of the thread. Basically it's for arrays, malloc(n *
> > sizeof(x)).
>
> well, make sure n is not 0. Its not that hard. I dont think I've *ever*
> had a situation where I wanted to pass 0 to malloc.
I would like to remind everyone that sizeof(x) can be 0 too. For
example, on Linux sizeof(spinlock_t) == 0 on UP. Anything where you
have a bunch of structure fields which depend on compile time
configuration, or where a type might be replaced by a stub empty
structure, is a possible sizeof(x) == 0.
> Its not that hard.
The fact is there are a number of bugs in qemu where n == 0 is not
checked prior to calling qemu_malloc() at the moment. None of them
are "hard" to fix - they are rare cases that nobody noticed when
writing them.
Until we have code analysis tools checking for that, bugs of that kind
will probably keep arising.
-- Jamie
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, (continued)
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Ian Molton, 2009/12/05
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Avi Kivity, 2009/12/06
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Ian Molton, 2009/12/06
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Avi Kivity, 2009/12/06
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, malc, 2009/12/06
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Avi Kivity, 2009/12/06
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, malc, 2009/12/06
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Avi Kivity, 2009/12/06
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, malc, 2009/12/06
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Ian Molton, 2009/12/06
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends,
Jamie Lokier <=
- Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Markus Armbruster, 2009/12/07
Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, malc, 2009/12/07
Re: [Qemu-devel] [PATCH] Permit zero-sized qemu_malloc() & friends, Anthony Liguori, 2009/12/07