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| author | Vitaly Mayatskikh <v.mayatskih@gmail.com> | 2017-09-22 01:18:39 -0400 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2017-11-11 13:33:37 +0000 |
| commit | 3c885aa3b459aabc5fa04251a5fdd88e29b1de70 (patch) | |
| tree | 05a3a52b97f648f54cb2c897bdadcddbfd65b717 /block | |
| parent | 7df83adfc5d38bf960ef7ff0e4cb1c2c92715f63 (diff) | |
| download | linux-stable-3c885aa3b459aabc5fa04251a5fdd88e29b1de70.tar.gz linux-stable-3c885aa3b459aabc5fa04251a5fdd88e29b1de70.tar.bz2 linux-stable-3c885aa3b459aabc5fa04251a5fdd88e29b1de70.zip | |
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: Ben Hutchings <ben@decadent.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 529e4195724e..dcc6365bcc11 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1337,6 +1337,7 @@ static 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; @@ -1351,6 +1352,13 @@ static 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; } |