Hi!
From: Kent Overstreet kent.overstreet@linux.dev
[ Upstream commit 168145f617d57bf4e474901b7ffa869337a802e6 ]
bio_iov_iter_get_pages() trims the IO based on the block size of the block device the IO will be issued to.
However, bcachefs is a multi device filesystem; when we're creating the bio we don't yet know which block device the bio will be submitted to - we have to handle the alignment checks elsewhere.
Thus this is needed to avoid a null ptr deref.
We are certainly not going to backport bcachefs to -stable. Please drop.
BR, Pavel
+++ b/block/bio.c @@ -1198,7 +1198,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) struct page **pages = (struct page **)bv; ssize_t size, left; unsigned len, i = 0;
- size_t offset, trim;
- size_t offset; int ret = 0;
/* @@ -1223,10 +1223,12 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) nr_pages = DIV_ROUND_UP(offset + size, PAGE_SIZE);
- trim = size & (bdev_logical_block_size(bio->bi_bdev) - 1);
- iov_iter_revert(iter, trim);
- if (bio->bi_bdev) {
size_t trim = size & (bdev_logical_block_size(bio->bi_bdev) - 1);iov_iter_revert(iter, trim);size -= trim;- }
- size -= trim; if (unlikely(!size)) { ret = -EFAULT; goto out;