On 06/07/2013 10:09 AM, Minchan Kim wrote:
> 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....@huawei.com>
>> Cc: sta...@vger.kernel.org
>> ---
>> 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?
I shall think so.
Jerome
>
>> return 0;
>> - }
>>
>> /* I/O request is valid */
>> return 1;
>> --
>> 1.8.1.2
>>
>> --
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