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    Subject[patch 15/51] dup2: Fix return value with oldfd == newfd and invalid fd
    2.6.29-stable review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Jeff Mahoney <jeffm@suse.com>

    commit 2b79bc4f7ebbd5af3c8b867968f9f15602d5f802 upstream.

    The return value of dup2 when oldfd == newfd and the fd isn't valid is
    not getting properly sign extended. We end up with 4294967287 instead
    of -EBADF.

    I've reproduced this on SLE11 (2.6.27.21), openSUSE Factory
    (2.6.29-rc5), and Ubuntu 9.04 (2.6.28).

    This patch uses a signed int for the error value so it is properly
    extended.

    Commit 6c5d0512a091480c9f981162227fdb1c9d70e555 introduced this
    regression.

    Reported-by: Jiri Dluhos <jdluhos@novell.com>
    Signed-off-by: Jeff Mahoney <jeffm@suse.com>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    fs/fcntl.c | 6 ++++--
    1 file changed, 4 insertions(+), 2 deletions(-)

    --- a/fs/fcntl.c
    +++ b/fs/fcntl.c
    @@ -117,11 +117,13 @@ SYSCALL_DEFINE2(dup2, unsigned int, oldf
    {
    if (unlikely(newfd == oldfd)) { /* corner case */
    struct files_struct *files = current->files;
    + int retval = oldfd;
    +
    rcu_read_lock();
    if (!fcheck_files(files, oldfd))
    - oldfd = -EBADF;
    + retval = -EBADF;
    rcu_read_unlock();
    - return oldfd;
    + return retval;
    }
    return sys_dup3(oldfd, newfd, 0);
    }



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