From: Jaegeuk Kim <jaegeuk@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Jaegeuk Kim <jaegeuk@kernel.org>, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org
Subject: [PATCH] loop: drop caches if offset is changed
Date: Fri, 14 Dec 2018 12:32:23 -0800 [thread overview]
Message-ID: <20181214203223.7063-1-jaegeuk@kernel.org> (raw)
If we don't drop caches used in old offset, we can get old data from new
offset, which gives unexpected data to user.
Martijn found a loopback bug in the below scenario.
1) LOOP_SET_FD loads first two pages on loop file
2) LOOP_SET_STATUS64 changes the offset on the loop file
3) mount is failed due to the cached pages having wrong superblock
This patch drops caches when we change lo->offset.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Reported-by: Martijn Coenen <maco@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
drivers/block/loop.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index cb0cc8685076..f073a3f1a7cd 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1154,6 +1154,12 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
if (lo->lo_offset != info->lo_offset ||
lo->lo_sizelimit != info->lo_sizelimit) {
+ struct block_device *bdev = lo->lo_device;
+
+ /* drop stale caches used in old offset */
+ sync_blockdev(bdev);
+ kill_bdev(bdev);
+
if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) {
err = -EFBIG;
goto exit;
--
2.19.0.605.g01d371f741-goog
next reply other threads:[~2018-12-14 20:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-14 20:32 Jaegeuk Kim [this message]
2018-12-17 19:42 ` [PATCH v2] loop: drop caches if offset or block_size are changed Jaegeuk Kim
2018-12-18 17:48 ` Jens Axboe
2018-12-18 22:41 ` [PATCH v3] " Jaegeuk Kim
2019-01-09 5:22 ` Jaegeuk Kim
2019-01-09 20:51 ` Bart Van Assche
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