[PATCH] mtd: mtd_oobtest: fix verify errors due to incorrect use of prandom_bytes_state()
Lothar Waßmann
LW at KARO-electronics.de
Wed Jan 22 09:09:59 EST 2014
Hi,
Is anyone taking care of this?
Lothar Waßmann wrote:
> When using prandom_bytes_state() it is critical to use the same block
> size in all invocations that are to produce the same random sequence.
> Otherwise the state of the PRNG will be out of sync if the blocksize
> is not divisible by 4.
> This leads to bogus verification errors in several tests which use
> different block sizes to initialize the buffer for writing and
> comparison.
>
> Signed-off-by: Lothar Waßmann <LW at KARO-electronics.de>
> ---
> drivers/mtd/tests/oobtest.c | 14 ++++++++++++--
> 1 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mtd/tests/oobtest.c b/drivers/mtd/tests/oobtest.c
> index 2e9e2d1..72c7359 100644
> --- a/drivers/mtd/tests/oobtest.c
> +++ b/drivers/mtd/tests/oobtest.c
> @@ -213,8 +213,15 @@ static int verify_eraseblock_in_one_go(int ebnum)
> int err = 0;
> loff_t addr = ebnum * mtd->erasesize;
> size_t len = mtd->ecclayout->oobavail * pgcnt;
> + int i;
> +
> + for (i = 0; i < pgcnt; i++)
> + prandom_bytes_state(&rnd_state, &writebuf[i * use_len],
> + use_len);
> + if (len % use_len)
> + prandom_bytes_state(&rnd_state, &writebuf[i * use_len],
> + len % use_len);
>
> - prandom_bytes_state(&rnd_state, writebuf, len);
> ops.mode = MTD_OPS_AUTO_OOB;
> ops.len = 0;
> ops.retlen = 0;
> @@ -594,7 +601,10 @@ static int __init mtd_oobtest_init(void)
> if (bbt[i] || bbt[i + 1])
> continue;
> prandom_bytes_state(&rnd_state, writebuf,
> - mtd->ecclayout->oobavail * 2);
> + mtd->ecclayout->oobavail);
> + prandom_bytes_state(&rnd_state,
> + writebuf + mtd->ecclayout->oobavail,
> + mtd->ecclayout->oobavail);
> addr = (i + 1) * mtd->erasesize - mtd->writesize;
> ops.mode = MTD_OPS_AUTO_OOB;
> ops.len = 0;
--
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