block: fix NULL pointer dereferenced within __blk_rq_map_sg

The block layer internal flush request may not have bio attached, so the
request iterator has to be initialized from valid req->bio, otherwise NULL
pointer dereferenced is triggered.

Cc: Christoph Hellwig <[email protected]>
Reported-and-tested-by: Cheyenne Wills <[email protected]>
Fixes: b7175e24d6ac ("block: add a dma mapping iterator")
Signed-off-by: Ming Lei <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions