diff options
| author | NeilBrown <neilb@suse.de> | 2014-07-31 13:54:54 +1000 |
|---|---|---|
| committer | NeilBrown <neilb@suse.de> | 2014-07-31 13:54:54 +1000 |
| commit | af5628f05db62c656f994b2346897939b5110d6a (patch) | |
| tree | d3157495b181dbb830fc44375130bde365037a25 | |
| parent | 2446dba03f9dabe0b477a126cbeb377854785b47 (diff) | |
md: disable probing for md devices 512 and over.
The way md devices are traditionally created in the kernel
is simply to open the device with the desired major/minor number.
This can be problematic as some support tools, notably udev and
programs run by udev, can open a device just to see what is there, and
find that it has created something. It is easy for a race to cause
udev to open an md device just after it was destroy, causing it to
suddenly re-appear.
For some time we have had an alternate way to create md devices
echo md_somename > /sys/modules/md_mod/paramaters/new_array
This will always use a minor number of 512 or higher, which mdadm
normally avoids.
Using this makes the creation-by-opening unnecessary, but does
not disable it, so it is still there to cause problems.
This patch disable probing for devices with a major of 9 (MD_MAJOR)
and a minor of 512 and up. This devices created by writing to
new_array cannot be re-created by opening the node in /dev.
Signed-off-by: NeilBrown <neilb@suse.de>
| -rw-r--r-- | drivers/md/md.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 32fc19c540d4..1379b1a3b9ff 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8592,7 +8592,7 @@ static int __init md_init(void) goto err_mdp; mdp_major = ret; - blk_register_region(MKDEV(MD_MAJOR, 0), 1UL<<MINORBITS, THIS_MODULE, + blk_register_region(MKDEV(MD_MAJOR, 0), 512, THIS_MODULE, md_probe, NULL, NULL); blk_register_region(MKDEV(mdp_major, 0), 1UL<<MINORBITS, THIS_MODULE, md_probe, NULL, NULL); @@ -8687,7 +8687,7 @@ static __exit void md_exit(void) struct list_head *tmp; int delay = 1; - blk_unregister_region(MKDEV(MD_MAJOR,0), 1U << MINORBITS); + blk_unregister_region(MKDEV(MD_MAJOR,0), 512); blk_unregister_region(MKDEV(mdp_major,0), 1U << MINORBITS); unregister_blkdev(MD_MAJOR,"md"); |