zram: set physical queue limits to avoid array out of bounds accesses

zram can handle at most SECTORS_PER_PAGE sectors in a bio's bvec. When using
the NVMe over Fabrics loopback target which potentially sends a huge bulk of
pages attached to the bio's bvec this results in a kernel panic because of
array out of bounds accesses in zram_decompress_page().

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index e27d89a36c34170d1c894b60f43ab3903a5fbf70..dceb5edd1e5455f4c1b101e8ad3ce4dba46ac22f 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1189,6 +1189,8 @@ static int zram_add(void)
        blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
        blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
        zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
+       zram->disk->queue->limits.max_sectors = SECTORS_PER_PAGE;
+       zram->disk->queue->limits.chunk_sectors = 0;
        blk_queue_max_discard_sectors(zram->disk->queue, UINT_MAX);
        /*
         * zram_bio_discard() will clear all logical blocks if logical block