diff options
| author | Brian Behlendorf <behlendorf1@llnl.gov> | 2013-05-24 15:55:28 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-06-07 12:52:41 -0700 |
| commit | f5427b0dd73d16f71ddfb6aeeec7dcfe1317c957 (patch) | |
| tree | 06cd336bacd87b3c2ba8936d6e93792a322cc345 | |
| parent | 1099653f81d892c69b69e8cb1af8dafb756fb9b2 (diff) | |
| download | lwn-f5427b0dd73d16f71ddfb6aeeec7dcfe1317c957.tar.gz lwn-f5427b0dd73d16f71ddfb6aeeec7dcfe1317c957.zip | |
drivers/block/brd.c: fix brd_lookup_page() race
commit dfd20b2b174d3a9b258ea3b7a35ead33576587b1 upstream.
The index on the page must be set before it is inserted in the radix
tree. Otherwise there is a small race which can occur during lookup
where the page can be found with the incorrect index. This will trigger
the BUG_ON() in brd_lookup_page().
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reported-by: Chris Wedgwood <cw@f00f.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/block/brd.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 531ceb31d0ff..4e8213aa02fd 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -117,13 +117,13 @@ static struct page *brd_insert_page(struct brd_device *brd, sector_t sector) spin_lock(&brd->brd_lock); idx = sector >> PAGE_SECTORS_SHIFT; + page->index = idx; if (radix_tree_insert(&brd->brd_pages, idx, page)) { __free_page(page); page = radix_tree_lookup(&brd->brd_pages, idx); BUG_ON(!page); BUG_ON(page->index != idx); - } else - page->index = idx; + } spin_unlock(&brd->brd_lock); radix_tree_preload_end(); |