Messages in this thread |  | | From | Ming Lei <> | Date | Mon, 7 Aug 2017 10:39:38 +0800 | Subject | Re: [PATCH] loop: fix to a race condition due to the early registration of device |
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On Thu, Aug 3, 2017 at 11:01 PM, Anton Volkov <avolkov@ispras.ru> wrote: > The early device registration made possible a race leading to allocations > of disks with wrong minors. > > This patch moves the device registration further down the loop_init > function to make the race infeasible. > > Found by Linux Driver Verification project (linuxtesting.org). > > Signed-off-by: Anton Volkov <avolkov@ispras.ru> > --- > drivers/block/loop.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index ef83349..2fbd4089 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -1996,10 +1996,6 @@ static int __init loop_init(void) > struct loop_device *lo; > int err; > > - err = misc_register(&loop_misc); > - if (err < 0) > - return err; > - > part_shift = 0; > if (max_part > 0) { > part_shift = fls(max_part); > @@ -2017,12 +2013,12 @@ static int __init loop_init(void) > > if ((1UL << part_shift) > DISK_MAX_PARTS) { > err = -EINVAL; > - goto misc_out; > + goto err_out; > } > > if (max_loop > 1UL << (MINORBITS - part_shift)) { > err = -EINVAL; > - goto misc_out; > + goto err_out; > } > > /* > @@ -2041,6 +2037,11 @@ static int __init loop_init(void) > range = 1UL << MINORBITS; > } > > + err = misc_register(&loop_misc); > + if (err < 0) > + goto err_out; > + > + > if (register_blkdev(LOOP_MAJOR, "loop")) { > err = -EIO; > goto misc_out; > @@ -2060,6 +2061,7 @@ static int __init loop_init(void) > > misc_out: > misc_deregister(&loop_misc); > +err_out: > return err; > } > > -- > 2.7.4 >
Looks fine:
Reviewed-by: Ming Lei <ming.lei@redhat.com>
BTW, this patch should have been CCed to linux-block mail list.
Thanks, Ming Lei
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