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mtd: mtdpart: disallow reading OOB past the end of the partition 

This patch fixes the mtdpart bug which allows users reading OOB past the
end of the partition. This happens because 'part_read_oob()' allows reading
multiple OOB areas in one go, and mtdparts does not validate the OOB
length in the request.

Although there is such check in 'nand_do_read_oob()' in nand_base.c, but
it checks that we do not read past the flash chip, not the partition,
because in nand_base.c we work with the whole chip (e.g., mtd->size
in nand_base.c is the size of the whole chip). So this check cannot
be done correctly in nand_base.c and should be instead done in mtdparts.c.

This problem was reported by Jason Liu <r64343@freescale.com> and reproduced
with nandsim:

$ modprobe nandsim first_id_byte=0x20 second_id_byte=0xaa third_id_byte=0x00 \
                   fourth_id_byte=0x15 parts=0x400,0x400
$ modprobe nandsim mtd_oobtest.ko dev=0
$ dmesg
= snip =
mtd_oobtest: attempting to read past end of device
mtd_oobtest: an error is expected...
mtd_oobtest: error: read past end of device
= snip =
mtd_oobtest: finished with 2 errors

Reported-by: Jason Liu <liu.h.jason@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
Artem Bityutskiy 2011-01-16 17:50:54 +02:00 committed by David Woodhouse
parent 52d039fdaa
commit 154bf89f5e
1 changed files with 18 additions and 1 deletions
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19
drivers/mtd/mtdpart.c
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@ -120,8 +120,25 @@ static int part_read_oob(struct mtd_info *mtd, loff_t from,
return -EINVAL;
if (ops->datbuf && from + ops->len > mtd->size)
return -EINVAL;
res = part->master->read_oob(part->master, from + part->offset, ops);
/*
* If OOB is also requested, make sure that we do not read past the end
* of this partition.
*/
if (ops->oobbuf) {
size_t len, pages;
if (ops->mode == MTD_OOB_AUTO)
len = mtd->oobavail;
else
len = mtd->oobsize;
pages = mtd_div_by_ws(mtd->size, mtd);
pages -= mtd_div_by_ws(from, mtd);
if (ops->ooboffs + ops->ooblen > pages * len)
return -EINVAL;
}
res = part->master->read_oob(part->master, from + part->offset, ops);
if (unlikely(res)) {
if (res == -EUCLEAN)
mtd->ecc_stats.corrected++;