Re: [PATCH 1/2] ras: fix an off-by-one error in __find_elem()

Borislav Petkov
2019-04-16T09:07:33Z

On Mon, Apr 15, 2019 at 06:20:00PM -0700, Cong Wang wrote:
> ce_arr.array[] is always within the range [0, ce_arr.n-1].
> However, the binary search code in __find_elem() uses ce_arr.n
> as the maximum index, which could lead to an off-by-one
> out-of-bound access when the element after the last is exactly
> the one just got deleted, that is, 'min' returned to caller as
> 'ce_arr.n'.

Sorry, I don't follow.

There's a debugfs interface in /sys/kernel/debug/ras/cec/ with which you
can input random PFNs and test the thing.

Show me pls how this can happen with an example.

Thx.

--
Regards/Gruss,
Boris.

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