Re: [PATCH][next] dm ioctl: rate limit a couple of ioctl based error messages

["Colin King (gmail)" <colin.i.king@xxxxxxxxx>]

On 24/10/2024 15:01, Mikulas Patocka wrote:
> Hi
>
> I'd like to ask - have you experienced these errors? What was the process
> that triggered them? Was it some robot that tests syscalls with random
> parameters?

I hit this when running stress-ng's dev test, this exercises various 
ioctls for race conditions.  It's not a major issue, just a corner case 
found when I was running some stress tests.

Colin

> Mikulas
>
>
> On Thu, 24 Oct 2024, Colin Ian King wrote:
>
> > It is possible to spam the kernel log with a misbehaving user process that
> > is passing incorrect dm ioctls to /dev/mapper/control. Use a rate limit
> > on these error messages to reduce the noise.
> >
> > Signed-off-by: Colin Ian King <colin.i.king@xxxxxxxxx>
> > ---
> >   drivers/md/dm-ioctl.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
> > index f299ff393a6a..d42eac944eb5 100644
> > --- a/drivers/md/dm-ioctl.c
> > +++ b/drivers/md/dm-ioctl.c
> > @@ -1912,7 +1912,7 @@ static int check_version(unsigned int cmd, struct dm_ioctl __user *user,
> >   
> >   	if ((kernel_params->version[0] != DM_VERSION_MAJOR) ||
> >   	    (kernel_params->version[1] > DM_VERSION_MINOR)) {
> > -		DMERR("ioctl interface mismatch: kernel(%u.%u.%u), user(%u.%u.%u), cmd(%d)",
> > +		DMERR_LIMIT("ioctl interface mismatch: kernel(%u.%u.%u), user(%u.%u.%u), cmd(%d)",
> >   		      DM_VERSION_MAJOR, DM_VERSION_MINOR,
> >   		      DM_VERSION_PATCHLEVEL,
> >   		      kernel_params->version[0],
> > @@ -1961,7 +1961,7 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern
> >   
> >   	if (unlikely(param_kernel->data_size < minimum_data_size) ||
> >   	    unlikely(param_kernel->data_size > DM_MAX_TARGETS * DM_MAX_TARGET_PARAMS)) {
> > -		DMERR("Invalid data size in the ioctl structure: %u",
> > +		DMERR_LIMIT("Invalid data size in the ioctl structure: %u",
> >   		      param_kernel->data_size);
> >   		return -EINVAL;
> >   	}
> > --
> > 2.39.5