dm ioctl: validate name length when renaming

commit bc0fd67feba2e0770aad85393500ba77c6489f1c upstream.

When renaming a mapped device validate the length of the new name.

The rename ioctl accepted any correctly-terminated string enclosed
within the data passed from userspace.  The other ioctls enforce a
size limit of DM_NAME_LEN.  If the name is changed and becomes longer
than that, the device can no longer be addressed by name.

Fix it by properly checking for device name length (including
terminating zero).

Signed-off-by: Milan Broz <mbroz@redhat.com>
Reviewed-by: Jonathan Brassow <jbrassow@redhat.com>
Reviewed-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 777c948180f9ae9b956f803eb92c659cb12b2937..c4819b6b77b2b64444e6855402d77d23aebb4c70 100644 (file)
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -704,7 +704,8 @@ static int dev_rename(struct dm_ioctl *param, size_t param_size)
        char *new_name = (char *) param + param->data_start;
 
        if (new_name < param->data ||
-           invalid_str(new_name, (void *) param + param_size)) {
+           invalid_str(new_name, (void *) param + param_size) ||
+           strlen(new_name) > DM_NAME_LEN - 1) {
                DMWARN("Invalid new logical volume name supplied.");
                return -EINVAL;
        }