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    SubjectRe: [patch] perfmon ia64: fix file/vma lifetime
    Nick,

    On Tue, Feb 20, 2007 at 04:08:45PM +0100, Nick Piggin wrote:
    > On Tue, Feb 20, 2007 at 06:34:54AM -0800, Stephane Eranian wrote:
    > > nick,
    > >
    > > On Tue, Feb 20, 2007 at 03:18:56PM +0100, Nick Piggin wrote:
    > > > From: Nick Piggin <npiggin@suse.de>
    > > >
    > > > Perfmon associates vmalloc()ed memory with a file descriptor, and installs
    > > > a vma mapping that memory. Unfortunately, the vm_file field is not filled in,
    > > > so processes with mappings to that memory do not prevent the file from being
    > > > closed and the memory freed. This results in use-after-free bugs and multiple
    > > > freeing of pages, etc.
    > > >
    > > > I saw this bug on an Altix on SLES9. Haven't reproduced upstream but it looks
    > > > like the same issue is there.
    > > >
    > >
    > > I think this is possible for the old perfmon v2.0 codebase that is currently in
    > > mainline for IA-64.
    >
    > OK, I take that as an Ack? (the patch definitely applies, I just can't
    > get the Altix to boot 2.6.20 to verify it).
    >
    > > I have corrected this with the multi-arch v2.3 code base
    > > available as a kernel patch for the moment.
    >
    > Not that I've looked at the code, but can I be hopeful that v2.3
    > using the traditional mmap file operation to set up the vma and map
    > in pages, rather than the way that v2.0 works?
    >

    It does. You need an explicit mmap() call.

    --

    -Stephane
    -
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