Re: [PATCH -net] tls: return -EFAULT if copy_to_user() fails

Joe Perches
2017-06-23T10:58:35Z

On Fri, 2017-06-23 at 13:36 +0300, Dan Carpenter wrote:
> On Fri, Jun 23, 2017 at 03:31:44AM -0700, Joe Perches wrote:
> > On Fri, 2017-06-23 at 13:15 +0300, Dan Carpenter wrote:
> > > The copy_to_user() function returns the number of bytes remaining but we
> > > want to return -EFAULT here.
> >
> > because?
> >
>
> Rhetorical questions don't work over email. Are you honestly confused
> by this patch?

There doesn't seem to be a fault here, just a
return of less than the expected number of bytes.

It's non-obvious why -EFAULT is the appropriate
return value.

Why is changing the return value from number of
bytes transferred, even if less than desired,
the right thing to do? Your commit message
doesn't describe any rationale.

getsockopt says:

For getsockopt(), optlen is a value-result argument, initially containing the size
of the buffer pointed to by optval, and modified on return to indicate the actual
size of the value returned

The generic EFAULT description in getsockopt is:

EFAULT The address pointed to by optval is not in a valid part of the
process address space. For getsockopt(), this error may also be
returned if optlen is not in a valid part of the process address
space.

Is tls different?

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