Re: do_sendfile ppos check ...

[Herbert Poetzl]

On Fri, Nov 04, 2005 at 01:36:36PM +1100, Herbert Xu wrote:
> Herbert Poetzl <herbert@xxxxxxxxxxxx> wrote:
> > 
> > which passes ppos as NULL, which in turn leads to an oops ...
> 
> But do_sendfile will set ppos to &in_file->f_pos if it's NULL.
> Why isn't that working?
> 
> > @@ -731,7 +731,8 @@ asmlinkage ssize_t sys_sendfile(int out_
> >                return ret;
> >        }
> > 
> > -       return do_sendfile(out_fd, in_fd, NULL, count, 0);
> > +       pos = 0;
> > +       return do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
> > }
> 
> The last argument is meant to be zero if you check the history.

hmm, why a different max than with offset?

currently investigating ... probably a removal of
the 'unnecessary' check (*ppos) would be a better
approach, something like:

--- linux-2.6/fs/read_write.c   2005-10-28 23:59:02.000000000 +0200
+++ linux-2.6/fs/read_write.c   2005-11-03 17:28:50.000000000 +0100
@@ -719,9 +719,6 @@
       	current->syscr++;
       	current->syscw++;

-       if (*ppos > max)
-               retval = -EOVERFLOW;
-
 fput_out:
         	ds,   fput_light(out_file, fput_needed_out);
 fput_in:

thanks for the input,
Herbert

> 
> Cheers,
> -- 
> Visit Openswan at http://www.openswan.org/
> Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
> Home Page: http://gondor.apana.org.au/~herbert/
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