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    SubjectRe: [PATCH] aio: fix io_setup/io_destroy race
    Date
    Al Viro <viro@ZenIV.linux.org.uk> writes:

    > Have ioctx_alloc() return an extra reference, so that caller would drop it
    > on success and not bother with re-grabbing it on failure exit. The current
    > code is obviously broken - io_destroy() from another thread that managed
    > to guess the address io_setup() would've returned would free ioctx right
    > under us; gets especially interesting if aio_context_t * we pass to
    > io_setup() points to PROT_READ mapping, so put_user() fails and we end
    > up doing io_destroy() on kioctx another thread has just got freed...

    Al, you certainly are creative. ;-) I agree with the problem and the
    fix. It would be nice, though if you had added comments.

    I ran xfstests ./check -g aio, and there were no problems.

    Reviewed-by: Jeff Moyer <jmoyer@redhat.com>


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