[PATCH] block: Fix potential page reference leak in __bio_iov_append_get_pages()

From: Miaohe Lin
Date: Sat Sep 05 2020 - 05:41:34 EST


When bio_add_hw_page() failed, we left page reference still held in pages.
Release these references and advance the iov_iter according to what we
have done successfully yet.

Fixes: 0512a75b98f8 ("block: Introduce REQ_OP_ZONE_APPEND")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
block/bio.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/block/bio.c b/block/bio.c
index e113073958cb..a323a5446221 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1080,7 +1080,7 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
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)
- return -EINVAL;
+ goto put_pages;
if (same_page)
put_page(page);
offset = 0;
@@ -1088,6 +1088,16 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)

iov_iter_advance(iter, size);
return 0;
+put_pages:
+ iov_iter_advance(iter, size - left);
+ for (; left > 0; left -= len, i++) {
+ struct page *page = pages[i];
+
+ len = min_t(size_t, PAGE_SIZE - offset, left);
+ put_page(page);
+ offset = 0;
+ }
+ return -EINVAL;
}

/**
--
2.19.1