1 files changed, 53 insertions, 3 deletions

diff --git a/block/bio.c b/block/bio.c
index 6a2f6fc3413e..5018a6fc2f36 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1221,10 +1221,45 @@ static int bio_iov_iter_align_down(struct bio *bio, struct iov_iter *iter,
 	return 0;
 }
 
+#ifdef CONFIG_DEBUG_KERNEL
+static inline bool bio_iov_bvec_aligned(const struct bio *bio,
+					unsigned mem_align_mask)
+{
+	struct bvec_iter iter;
+	struct bio_vec bv;
+
+	/*
+	 * Correct callers never break the alignment requirements, so this
+	 * exhaustive check is only paid for in debug builds.
+	 */
+	for_each_mp_bvec(bv, bio->bi_io_vec, iter, bio->bi_iter)
+		if ((bv.bv_offset | bv.bv_len) & mem_align_mask)
+			return false;
+	return true;
+}
+#else
+static inline bool bio_iov_bvec_aligned(const struct bio *bio,
+					unsigned mem_align_mask)
+{
+	/*
+	 * We forward the bio_vec as-is, so ITER_BVEC callers must provide
+	 * segments already aligned to the device's DMA alignment. The only
+	 * unchecked user-controllable offset that reaches here is an io_uring
+	 * registered buffer where just the first segment can be unaligned
+	 * (the rest is virtually contiguous), so checking only that one is
+	 * sufficient to know if the entire vector is valid.
+	 */
+	return !(mp_bvec_iter_offset(bio->bi_io_vec, bio->bi_iter) &
+							mem_align_mask);
+}
+#endif
+
 /**
  * bio_iov_iter_get_pages - add user or kernel pages to a bio
  * @bio: bio to add pages to
  * @iter: iov iterator describing the region to be added
+ * @mem_align_mask: the mask the source address and length must be aligned to,
+ *	0 for no requirement
  * @len_align_mask: the mask to align the total size to, 0 for any length
  *
  * This takes either an iterator pointing to user memory, or one pointing to
@@ -1243,7 +1278,7 @@ static int bio_iov_iter_align_down(struct bio *bio, struct iov_iter *iter,
  * is returned only if 0 pages could be pinned.
  */
 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter,
-			   unsigned len_align_mask)
+			   unsigned mem_align_mask, unsigned len_align_mask)
 {
 	iov_iter_extraction_t flags = 0;
 
@@ -1252,6 +1287,10 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter,
 
 	if (iov_iter_is_bvec(iter)) {
 		bio_iov_bvec_set(bio, iter);
+
+		if (!bio_iov_bvec_aligned(bio, mem_align_mask))
+			return -EINVAL;
+
 		iov_iter_advance(iter, bio->bi_iter.bi_size);
 		return 0;
 	}
@@ -1266,8 +1305,19 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter,
 
 		ret = iov_iter_extract_bvecs(iter, bio->bi_io_vec,
 				BIO_MAX_SIZE - bio->bi_iter.bi_size,
-				&bio->bi_vcnt, bio->bi_max_vecs, flags);
+				&bio->bi_vcnt, bio->bi_max_vecs,
+				mem_align_mask, flags);
 		if (ret <= 0) {
+			/*
+			 * A misaligned vector fails the whole I/O.  Release any
+			 * pages pinned by earlier iterations before returning
+			 * since this bio won't be submitted to release them.
+			 */
+			if (ret == -EINVAL) {
+				bio_release_pages(bio, false);
+				bio_clear_flag(bio, BIO_PAGE_PINNED);
+				bio->bi_vcnt = 0;
+			}
 			if (!bio->bi_vcnt)
 				return ret;
 			break;
@@ -1380,7 +1430,7 @@ static int bio_iov_iter_bounce_read(struct bio *bio, struct iov_iter *iter,
 
 	do {
 		ret = iov_iter_extract_bvecs(iter, bio->bi_io_vec + 1, len,
-				&bio->bi_vcnt, bio->bi_max_vecs - 1, 0);
+				&bio->bi_vcnt, bio->bi_max_vecs - 1, 0, 0);
 		if (ret <= 0) {
 			if (!bio->bi_vcnt)
 				goto out_folio_put;