From: Paolo Bonzini <pbonzini@redhat.com>
To: Stefano Bonifazi <stefboombastic@gmail.com>
Cc: qemu-devel@nongnu.org
Subject: [Qemu-devel] Re: [PATCH] fix qruncom compilation problems
Date: Fri, 10 Dec 2010 09:53:04 +0100 [thread overview]
Message-ID: <4D01EA70.1040906@redhat.com> (raw)
In-Reply-To: <4D0111E5.5070702@gmail.com>
On 12/09/2010 06:29 PM, Stefano Bonifazi wrote:
> how can one think that addresses around zero are free for a mapping??
Addresses around zero are always free, because if they weren't you
couldn't detect NULL pointer dereferences reliably.
mmap-ing at zero thus is a tricky operation, because it removes the
possibility to detect NULL pointer dereferences. What's worse, such
ability would be lost even for _kernel_ dereferences of NULL, thus
opening a large security hole for privilege-escalation or kernel
exploits. So, mmap-ing addresses close to zero is restricted to root.
Paolo
next prev parent reply other threads:[~2010-12-10 8:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-08 11:39 [Qemu-devel] Compiling tests/qruncom.c Stefano Bonifazi
2010-12-08 12:49 ` [Qemu-devel] [PATCH] fix qruncom compilation problems Paolo Bonzini
2010-12-08 21:43 ` [Qemu-devel] " Stefano Bonifazi
2010-12-09 7:16 ` Paolo Bonzini
2010-12-09 17:29 ` Stefano Bonifazi
2010-12-10 8:53 ` Paolo Bonzini [this message]
2010-12-10 21:43 ` Stefano Bonifazi
[not found] ` <4D02A030.6080400@redhat.com>
2010-12-11 14:42 ` [Qemu-devel] " Stefano Bonifazi
2010-12-13 8:27 ` [Qemu-devel] " Paolo Bonzini
2010-12-09 3:32 ` [Qemu-devel] " Isaku Yamahata
2010-12-09 7:16 ` Paolo Bonzini
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