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| author | Vitaly Mayatskikh <v.mayatskih@gmail.com> | 2017-09-22 01:18:39 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-10-18 09:15:16 +0200 |
| commit | d7795bf6a9d8b004dbbd1f081f3eff18ff49276d (patch) | |
| tree | 21fdc6eb65027f72ee7ade13aebfabd9a3cc1284 /block | |
| parent | 2159252e70e95ba59e926423a006b95c313a0eea (diff) | |
| download | linux-stable-d7795bf6a9d8b004dbbd1f081f3eff18ff49276d.tar.gz linux-stable-d7795bf6a9d8b004dbbd1f081f3eff18ff49276d.tar.bz2 linux-stable-d7795bf6a9d8b004dbbd1f081f3eff18ff49276d.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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 78803e99c154..140c45b2b717 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1338,6 +1338,7 @@ 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; @@ -1352,6 +1353,13 @@ 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; } |