diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2023-08-09 12:44:20 +0200 |
|---|---|---|
| committer | Mike Snitzer <snitzer@kernel.org> | 2023-09-14 11:18:29 -0400 |
| commit | f6007dce0cd35d634d9be91ef3515a6385dcee16 (patch) | |
| tree | 663ba934a3a55514c73ef0e397c994ac3e4a3358 /drivers/md/dm-ioctl.c | |
| parent | 0bb80ecc33a8fb5a682236443c1e740d5c917d1d (diff) | |
| download | lwn-f6007dce0cd35d634d9be91ef3515a6385dcee16.tar.gz lwn-f6007dce0cd35d634d9be91ef3515a6385dcee16.zip | |
dm: fix a race condition in retrieve_deps
There's a race condition in the multipath target when retrieve_deps
races with multipath_message calling dm_get_device and dm_put_device.
retrieve_deps walks the list of open devices without holding any lock
but multipath may add or remove devices to the list while it is
running. The end result may be memory corruption or use-after-free
memory access.
See this description of a UAF with multipath_message():
https://listman.redhat.com/archives/dm-devel/2022-October/052373.html
Fix this bug by introducing a new rw semaphore "devices_lock". We grab
devices_lock for read in retrieve_deps and we grab it for write in
dm_get_device and dm_put_device.
Reported-by: Luo Meng <luomeng12@huawei.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Tested-by: Li Lingfeng <lilingfeng3@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Diffstat (limited to 'drivers/md/dm-ioctl.c')
| -rw-r--r-- | drivers/md/dm-ioctl.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index f5ed729a8e0c..21ebb6c39394 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1630,6 +1630,8 @@ static void retrieve_deps(struct dm_table *table, struct dm_dev_internal *dd; struct dm_target_deps *deps; + down_read(&table->devices_lock); + deps = get_result_buffer(param, param_size, &len); /* @@ -1644,7 +1646,7 @@ static void retrieve_deps(struct dm_table *table, needed = struct_size(deps, dev, count); if (len < needed) { param->flags |= DM_BUFFER_FULL_FLAG; - return; + goto out; } /* @@ -1656,6 +1658,9 @@ static void retrieve_deps(struct dm_table *table, deps->dev[count++] = huge_encode_dev(dd->dm_dev->bdev->bd_dev); param->data_size = param->data_start + needed; + +out: + up_read(&table->devices_lock); } static int table_deps(struct file *filp, struct dm_ioctl *param, size_t param_size) |