From 154bf89f5e3e3dc59666926f27ca4a0866f39157 Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Sun, 16 Jan 2011 17:50:54 +0200 Subject: 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 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 Signed-off-by: Artem Bityutskiy Signed-off-by: David Woodhouse --- drivers/mtd/mtdpart.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c index b910a37baed8..0a4760174782 100644 --- a/drivers/mtd/mtdpart.c +++ b/drivers/mtd/mtdpart.c @@ -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++; -- cgit v1.2.2