diff options
| author | Vitaly Mayatskikh <v.mayatskih@gmail.com> | 2017-09-22 01:18:39 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2017-10-10 23:54:51 -0400 |
| commit | 95d78c28b5a85bacbc29b8dba7c04babb9b0d467 (patch) | |
| tree | 171528916186018b071110eced6ebc55f5d6b3c3 /block | |
| parent | 899f0429c7d3eed886406cd72182bee3b96aa1f9 (diff) | |
| download | lwn-95d78c28b5a85bacbc29b8dba7c04babb9b0d467.tar.gz lwn-95d78c28b5a85bacbc29b8dba7c04babb9b0d467.zip | |
fix unbalanced page refcounting in bio_map_user_iov
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.
Cc: stable@vger.kernel.org
Signed-off-by: Vitaly Mayatskikh <v.mayatskih@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'block')
| -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 b38e962fa83e..0d6439e89acb 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1383,6 +1383,7 @@ struct bio *bio_map_user_iov(struct request_queue *q, offset = offset_in_page(uaddr); 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; @@ -1397,6 +1398,13 @@ 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; } |