[PATCH 5.13 272/300] bio: fix page leak bio_add_hw_page failure

Greg Kroah-Hartman
2021-09-13T14:20:39Z

From: Pavel Begunkov <asml.silence@gmail.com>

commit d9cf3bd531844ffbfe94b16e417037a16efc988d upstream.

__bio_iov_append_get_pages() doesn't put not appended pages on
bio_add_hw_page() failure, so potentially leaking them, fix it. Also, do
the same for __bio_iov_iter_get_pages(), even though it looks like it
can't be triggered by userspace in this case.

Fixes: 0512a75b98f8 ("block: Introduce REQ_OP_ZONE_APPEND")
Cc: stable@vger.kernel.org # 5.8+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1edfa6a2ffd66d55e6345a477df5387d2c1415d0.1626653825.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
block/bio.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

--- a/block/bio.c
+++ b/block/bio.c
@@ -979,6 +979,14 @@ static int bio_iov_bvec_set_append(struc
return 0;
}

+static void bio_put_pages(struct page **pages, size_t size, size_t off)
+{
+ size_t i, nr = DIV_ROUND_UP(size + (off & ~PAGE_MASK), PAGE_SIZE);
+
+ for (i = 0; i < nr; i++)
+ put_page(pages[i]);
+}
+
#define PAGE_PTRS_PER_BVEC (sizeof(struct bio_vec) / sizeof(struct page *))

/**
@@ -1023,8 +1031,10 @@ static int __bio_iov_iter_get_pages(stru
if (same_page)
put_page(page);
} else {
- if (WARN_ON_ONCE(bio_full(bio, len)))
- return -EINVAL;
+ if (WARN_ON_ONCE(bio_full(bio, len))) {
+ bio_put_pages(pages + i, left, offset);
+ return -EINVAL;
+ }
__bio_add_page(bio, page, len, offset);
}
offset = 0;
@@ -1069,6 +1079,7 @@ static int __bio_iov_append_get_pages(st
len = min_t(size_t, PAGE_SIZE - offset, left);
if (bio_add_hw_page(q, bio, page, len, offset,
max_append_sectors, &same_page) != len) {
+ bio_put_pages(pages + i, left, offset);
ret = -EINVAL;
break;
}