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Commit 12a7ad3b authored by Jiang Liu's avatar Jiang Liu Committed by Greg Kroah-Hartman
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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: default avatarJiang Liu <jiang.liu@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 65c48460

drivers/staging/zram/zram_drv.c

+12 −5
Original line number Diff line number Diff line
@@ -420,13 +420,20 @@ static void __zram_make_request(struct zram *zram, struct bio *bio, int rw) 
 */

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;