blk_rq_map_user_bvec currently only has ad-hoc checks for queue limits,
and the last fix to it enabled valid NVMe I/O to pass, but also allowed
invalid one for drivers that set a max_segment_size or seg_boundary
limit.
Fix it once for all by using the bio_split_rw_at helper from the I/O
path that indicates if and where a bio would be have to be split to
adhere to the queue limits, and it it returns a positive value, turn
that into -EREMOTEIO to retry using the copy path.
Fixes: 2ff949441802 ("block: fix sanity checks in blk_rq_map_user_bvec")
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
Changes since v1:
- correctly shift the max_hw_sectors value. Tested by actually
checking for max_hw_sectors exceeding I/Os to fail properly
block/blk-map.c | 56 +++++++++++++++----------------------------------
1 file changed, 17 insertions(+), 39 deletions(-)
diff --git a/block/blk-map.c b/block/blk-map.c
index 6ef2ec1f7d78..b5fd1d857461 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -561,55 +561,33 @@ EXPORT_SYMBOL(blk_rq_append_bio);
/* Prepare bio for passthrough IO given ITER_BVEC iter */
static int blk_rq_map_user_bvec(struct request *rq, const struct iov_iter *iter)
{
- struct request_queue *q = rq->q;
- size_t nr_iter = iov_iter_count(iter);
- size_t nr_segs = iter->nr_segs;
- struct bio_vec *bvecs, *bvprvp = NULL;
- const struct queue_limits *lim = &q->limits;
- unsigned int nsegs = 0, bytes = 0;
+ const struct queue_limits *lim = &rq->q->limits;
+ unsigned int max_bytes = lim->max_hw_sectors << SECTOR_SHIFT;
+ unsigned int nsegs;
struct bio *bio;
- size_t i;
+ int ret;
- if (!nr_iter || (nr_iter >> SECTOR_SHIFT) > queue_max_hw_sectors(q))
- return -EINVAL;
- if (nr_segs > queue_max_segments(q))
+ if (!iov_iter_count(iter) || iov_iter_count(iter) > max_bytes)
return -EINVAL;
- /* no iovecs to alloc, as we already have a BVEC iterator */
+ /* reuse the bvecs from the iterator instead of allocating new ones */
bio = blk_rq_map_bio_alloc(rq, 0, GFP_KERNEL);
- if (bio == NULL)
+ if (!bio)
return -ENOMEM;
-
bio_iov_bvec_set(bio, (struct iov_iter *)iter);
- blk_rq_bio_prep(rq, bio, nr_segs);
-
- /* loop to perform a bunch of sanity checks */
- bvecs = (struct bio_vec *)iter->bvec;
- for (i = 0; i < nr_segs; i++) {
- struct bio_vec *bv = &bvecs[i];
-
- /*
- * If the queue doesn't support SG gaps and adding this
- * offset would create a gap, fallback to copy.
- */
- if (bvprvp && bvec_gap_to_prev(lim, bvprvp, bv->bv_offset)) {
- blk_mq_map_bio_put(bio);
- return -EREMOTEIO;
- }
- /* check full condition */
- if (nsegs >= nr_segs || bytes > UINT_MAX - bv->bv_len)
- goto put_bio;
- if (bytes + bv->bv_len > nr_iter)
- break;
- nsegs++;
- bytes += bv->bv_len;
- bvprvp = bv;
+ /* check that the data layout matches the hardware restrictions */
+ ret = bio_split_rw_at(bio, lim, &nsegs, max_bytes);
+ if (ret) {
+ /* if we would have to split the bio, copy instead */
+ if (ret > 0)
+ ret = -EREMOTEIO;
+ blk_mq_map_bio_put(bio);
+ return ret;
}
+
+ blk_rq_bio_prep(rq, bio, nsegs);
return 0;
-put_bio:
- blk_mq_map_bio_put(bio);
- return -EINVAL;
}
/**
--
2.45.2
