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    SubjectRe: [PATCH] zram: fix null dereference of handle
    Hi Minchan,

    On (09/19/17 15:59), Minchan Kim wrote:
    [..]
    > > another question, "!handle == value & ZRAM_SAME"? if so, then why not
    > > just check for `flags & ZRAM_SAME'? if not then:
    > >
    > > - for `value & ZRAM_SAME' you fill the page with zram_get_element(zram, index)
    > > and return 0. ok.
    > >
    > > - for !handle.... you also fill the page with zram_get_element(zram, index)
    > > and return 0. is this ok? shouldn't !handle return error in this case?
    >
    > We discussed it before that we shouldn't return error.
    > Userspace can ask reading unallocated buffer freely.

    ok, so this is intentional behaviour.

    > And in this case, it fills the buffer zero because handle and element is unified.
    > However, if your concern is readability, I will make it more explict.

    correct.
    ... but I thought that we would also return an error.

    > > I really suspect that there are some paths that can lead to !handle
    > > entry, that will not be ZRAM_SAME. e.g. error return from compression
    > > path.
    >
    > Could you be more specific?

    I just meant that there are error paths in zram write, which will leave
    us both with !handle entries and !ZRAM_SAME. but it seems that this is
    the intentional behaviour.

    -ss

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