linux-kernel - [PATCH 3.16 100/204] more bio_map_user

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Date:   Thu, 28 Dec 2017 17:05:44 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Al Viro" <viro@...iv.linux.org.uk>
Subject: [PATCH 3.16 100/204] more bio_map_user_iov() leak fixes

3.16.52-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@...iv.linux.org.uk>

commit 2b04e8f6bbb196cab4b232af0f8d48ff2c7a8058 upstream.

we need to take care of failure exit as well - pages already
in bio should be dropped by analogue of bio_unmap_pages(),
since their refcounts had been bumped only once per reference
in bio.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 block/bio.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

--- a/block/bio.c
+++ b/block/bio.c
@@ -1286,6 +1286,7 @@ static struct bio *__bio_map_user_iov(st
 	struct bio *bio;
 	int cur_page = 0;
 	int ret, offset;
+	struct bio_vec *bvec;
 
 	for (i = 0; i < iov_count; i++) {
 		unsigned long uaddr = (unsigned long)iov[i].iov_base;
@@ -1329,7 +1330,12 @@ static struct bio *__bio_map_user_iov(st
 
 		ret = get_user_pages_fast(uaddr, local_nr_pages,
 				write_to_vm, &pages[cur_page]);
-		if (ret < local_nr_pages) {
+		if (unlikely(ret < local_nr_pages)) {
+			for (j = cur_page; j < page_limit; j++) {
+				if (!pages[j])
+					break;
+				put_page(pages[j]);
+			}
 			ret = -EFAULT;
 			goto out_unmap;
 		}
@@ -1384,10 +1390,8 @@ static struct bio *__bio_map_user_iov(st
 	return bio;
 
  out_unmap:
-	for (i = 0; i < nr_pages; i++) {
-		if(!pages[i])
-			break;
-		page_cache_release(pages[i]);
+	bio_for_each_segment_all(bvec, bio, j) {
+		put_page(bvec->bv_page);
 	}
  out:
 	kfree(pages);