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author | Vitaly Mayatskikh <v.mayatskih@gmail.com> | 2017-09-22 08:18:39 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-10-18 10:38:31 +0300 |
commit | ffe1d63bc4570ee980a59996667c296c5be7252e (patch) | |
tree | babfd677dd4d4714868240139b4cfe44af786078 | |
parent | 287614d0f6c1497e7a38bb4a2eb28a6c2daf6791 (diff) | |
download | linux-ffe1d63bc4570ee980a59996667c296c5be7252e.tar.xz |
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 9a63597aaacc..963accba165c 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1379,6 +1379,7 @@ 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; @@ -1393,6 +1394,13 @@ 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; } |