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| author | Yufen Yu <yuyufen@huawei.com> | 2019-04-02 15:06:34 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-31 16:46:18 +0300 |
| commit | ad393793794efc3770a14727880738f7ee4d636b (patch) | |
| tree | 475417044946743159b01d2b72ca884a6e797425 /include/linux/genhd.h | |
| parent | 30f8da71c730491046836d50de4bdc5891eff57a (diff) | |
| download | linux-ad393793794efc3770a14727880738f7ee4d636b.tar.xz | |
block: fix use-after-free on gendisk
[ Upstream commit 2c88e3c7ec32d7a40cc7c9b4a487cf90e4671bdd ]
commit 2da78092dda "block: Fix dev_t minor allocation lifetime"
specifically moved blk_free_devt(dev->devt) call to part_release()
to avoid reallocating device number before the device is fully
shutdown.
However, it can cause use-after-free on gendisk in get_gendisk().
We use md device as example to show the race scenes:
Process1 Worker Process2
md_free
blkdev_open
del_gendisk
add delete_partition_work_fn() to wq
__blkdev_get
get_gendisk
put_disk
disk_release
kfree(disk)
find part from ext_devt_idr
get_disk_and_module(disk)
cause use after free
delete_partition_work_fn
put_device(part)
part_release
remove part from ext_devt_idr
Before <devt, hd_struct pointer> is removed from ext_devt_idr by
delete_partition_work_fn(), we can find the devt and then access
gendisk by hd_struct pointer. But, if we access the gendisk after
it have been freed, it can cause in use-after-freeon gendisk in
get_gendisk().
We fix this by adding a new helper blk_invalidate_devt() in
delete_partition() and del_gendisk(). It replaces hd_struct
pointer in idr with value 'NULL', and deletes the entry from
idr in part_release() as we do now.
Thanks to Jan Kara for providing the solution and more clear comments
for the code.
Fixes: 2da78092dda1 ("block: Fix dev_t minor allocation lifetime")
Cc: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include/linux/genhd.h')
| -rw-r--r-- | include/linux/genhd.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/genhd.h b/include/linux/genhd.h index f767293b00e6..f13272d84332 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -596,6 +596,7 @@ struct unixware_disklabel { extern int blk_alloc_devt(struct hd_struct *part, dev_t *devt); extern void blk_free_devt(dev_t devt); +extern void blk_invalidate_devt(dev_t devt); extern dev_t blk_lookup_devt(const char *name, int partno); extern char *disk_name (struct gendisk *hd, int partno, char *buf); |