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[SRU,Trusty,2/2] more bio_map_user_iov() leak fixes

Message ID 20171208133756.18662-3-kleber.souza@canonical.com
State New
Headers show
Series None | expand

Commit Message

Kleber Sacilotto de Souza Dec. 8, 2017, 1:37 p.m. UTC 
From: Al Viro <viro@zeniv.linux.org.uk>

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.

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

CVE-2017-12190
(backported from commit 2b04e8f6bbb196cab4b232af0f8d48ff2c7a8058)
[klebers:
 - Fixed file path from block/bio.c to fs/bio.c.
 - page_cache_release() is defined as put_page(), but keep it as
   page_cache_release() for consistency with the rest of the code.]
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
---
 fs/bio.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)
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Patch

diff --git a/fs/bio.c b/fs/bio.c
index 3311aa0f3dd9..2dde9b514b1c 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -1234,6 +1234,7 @@  static struct bio *__bio_map_user_iov(struct request_queue *q,
 	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;
@@ -1277,7 +1278,12 @@  static struct bio *__bio_map_user_iov(struct request_queue *q,
 
 		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;
 		}
@@ -1332,10 +1338,8 @@  static struct bio *__bio_map_user_iov(struct request_queue *q,
 	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, i) {
+		page_cache_release(bvec->bv_page);
 	}
  out:
 	kfree(pages);