| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.4 105/214] zram: avoid access beyond the zram device | Date | Wed, 4 Jun 2014 21:17:48 -0700 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: Jiang Liu <liuj97@gmail.com>
commit 12a7ad3b810e77137d0caf97a6dd97591e075b30 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Jianguo Wu <wujianguo@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/staging/zram/zram_drv.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)
--- a/drivers/staging/zram/zram_drv.c +++ b/drivers/staging/zram/zram_drv.c @@ -535,13 +535,20 @@ 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;
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