Commit 3e1de31b authored Sep 14, 2016 by Bart Van Assche Committed by Jens Axboe Sep 14, 2016

block: Improve bio_set_op_attrs() robustness



Since REQ_OP_BITS == 3 and __REQ_NR_BITS == 30 it is not that hard
to pass an op_flags argument to bio_set_op_attrs() that is larger
than the number of bits reserved for the op_flags argument. Complain
if this happens. Additionally, ensure that negative arguments trigger
a complaint (1 << ... is signed while 1U << ... is unsigned; adding
0U to an integer expression causes it to be promoted to an unsigned
type).

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Mike Christie <mchristi@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Damien Le Moal <damien.lemoal@hgst.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

parent 4382e33a

include/linux/blk_types.h

+12 −5

Original line number	Diff line number	Diff line
		@@ -94,10 +94,17 @@ struct bio {
		#define bio_op(bio) ((bio)->bi_opf >> BIO_OP_SHIFT)

		#define bio_set_op_attrs(bio, op, op_flags) do { \
		WARN_ON(op >= (1 << REQ_OP_BITS)); \
		if (__builtin_constant_p(op)) \
		BUILD_BUG_ON((op) + 0U >= (1U << REQ_OP_BITS)); \
		else \
		WARN_ON_ONCE((op) + 0U >= (1U << REQ_OP_BITS)); \
		if (__builtin_constant_p(op_flags)) \
		BUILD_BUG_ON((op_flags) + 0U >= (1U << BIO_OP_SHIFT)); \
		else \
		WARN_ON_ONCE((op_flags) + 0U >= (1U << BIO_OP_SHIFT)); \
		(bio)->bi_opf = bio_flags(bio); \
		(bio)->bi_opf \|= ((unsigned int) (op) << BIO_OP_SHIFT); \
		(bio)->bi_opf \|= op_flags; \
		(bio)->bi_opf \|= (((op) + 0U) << BIO_OP_SHIFT); \
		(bio)->bi_opf \|= (op_flags); \
		} while (0)

		#define BIO_RESET_BYTES offsetof(struct bio, bi_max_vecs)