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zram: avoid access beyond the zram device 

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@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiang Liu 2013-06-07 00:07:26 +08:00 committed by Greg Kroah-Hartman
parent 65c484609a
commit 12a7ad3b81
1 changed files with 13 additions and 6 deletions
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19
drivers/staging/zram/zram_drv.c
View File

@ -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))
return 0;
}
/* I/O request is valid */
return 1;