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block: fix queue limits checks in blk_rq_map_user_bvec for real

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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 returns a positive value, turn that
into -EREMOTEIO to retry using the copy path.

Fixes: 2ff9494418 ("block: fix sanity checks in blk_rq_map_user_bvec")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20241028090840.446180-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2024-10-28 10:07:48 +01:00 committed by Jens Axboe
parent 2ff9494418
commit be0e822bb3
1 changed files with 17 additions and 39 deletions
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56
block/blk-map.c
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@ -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;
}
/**