diff options
| author | Vitaly Mayatskikh <v.mayatskih@gmail.com> | 2017-09-22 01:18:39 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-10-18 09:20:42 +0200 |
| commit | 399c46095eb5d41934c8a99732028a9f1cf0ac50 (patch) | |
| tree | 5724438d3693af6c5fe4747cf8474821bd5e1f57 | |
| parent | f3b538493e665aa083388818b975ccf27979dec6 (diff) | |
fix unbalanced page refcounting in bio_map_user_iov
commit 95d78c28b5a85bacbc29b8dba7c04babb9b0d467 upstream.
bio_map_user_iov and bio_unmap_user do unbalanced pages refcounting if
IO vector has small consecutive buffers belonging to the same page.
bio_add_pc_page merges them into one, but the page reference is never
dropped.
Signed-off-by: Vitaly Mayatskikh <v.mayatskih@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | block/bio.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/block/bio.c b/block/bio.c index 14263fab94d3..68bbc835bacc 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1320,6 +1320,7 @@ struct bio *bio_map_user_iov(struct request_queue *q, offset = uaddr & ~PAGE_MASK; for (j = cur_page; j < page_limit; j++) { unsigned int bytes = PAGE_SIZE - offset; + unsigned short prev_bi_vcnt = bio->bi_vcnt; if (len <= 0) break; @@ -1334,6 +1335,13 @@ struct bio *bio_map_user_iov(struct request_queue *q, bytes) break; + /* + * check if vector was merged with previous + * drop page reference if needed + */ + if (bio->bi_vcnt == prev_bi_vcnt) + put_page(pages[j]); + len -= bytes; offset = 0; } |