On Fri, Jun 07, 2013 at 12:07:26AM +0800, Jiang Liu wrote:
> Function valid_io_request() should verify the entire request are within
> the zram device address range. Otherwise it may cause invalid memory
> access when accessing/modifying zram->meta->table[index] because the
> 'index' is out of range. Then it may access non-exist memory, randomly
> modify memory belong to other subsystems, which is hard to track down.
>
> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/staging/zram/zram_drv.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
> index 27ab824..9289217 100644
> --- a/drivers/staging/zram/zram_drv.c
> +++ b/drivers/staging/zram/zram_drv.c
> @@ -420,13 +420,20 @@ out:
> */
> static inline int valid_io_request(struct zram *zram, struct bio *bio)
> {
> - if (unlikely(
> - (bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
> - (bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)) ||
> - (bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))) {
> + u64 start, end, bound;
> +
> + /* unaligned request */
> + if (unlikely(bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
> + return 0;
> + if (unlikely(bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
> + return 0;
>
> + start = bio->bi_sector;
> + end = start + (bio->bi_size >> SECTOR_SHIFT);
> + bound = zram->disksize >> SECTOR_SHIFT;
> + /* out of range range */
> + if (unlikely(start >= bound || end >= bound || start > end))
if (end >= bound || start > end) isn't enough?
> return 0;
> - }
>
> /* I/O request is valid */
> return 1;
> --
> 1.8.1.2
>
> --
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--
Kind regards,
Minchan Kim
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