Messages in this thread | | | Date | Wed, 17 Feb 2021 23:40:00 +0530 | From | Atul Gopinathan <> | Subject | Re: [PATCH] staging: comedi: cast to (unsigned int *) |
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On Wed, Feb 17, 2021 at 06:35:15PM +0100, Greg KH wrote: > On Wed, Feb 17, 2021 at 10:29:08PM +0530, Atul Gopinathan wrote: > > Resolve the following warning generated by sparse: > > > > drivers/staging//comedi/comedi_fops.c:2956:23: warning: incorrect type in assignment (different address spaces) > > drivers/staging//comedi/comedi_fops.c:2956:23: expected unsigned int *chanlist > > drivers/staging//comedi/comedi_fops.c:2956:23: got void [noderef] <asn:1> * > > > > compat_ptr() has a return type of "void __user *" > > as defined in "include/linux/compat.h" > > > > cmd->chanlist is of type "unsigned int *" as defined > > in drivers/staging/comedi/comedi.h" in struct > > comedi_cmd. > > > > Signed-off-by: Atul Gopinathan <atulgopinathan@gmail.com> > > --- > > drivers/staging/comedi/comedi_fops.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c > > index e85a99b68f31..fc4ec38012b4 100644 > > --- a/drivers/staging/comedi/comedi_fops.c > > +++ b/drivers/staging/comedi/comedi_fops.c > > @@ -2953,7 +2953,7 @@ static int get_compat_cmd(struct comedi_cmd *cmd, > > cmd->scan_end_arg = v32.scan_end_arg; > > cmd->stop_src = v32.stop_src; > > cmd->stop_arg = v32.stop_arg; > > - cmd->chanlist = compat_ptr(v32.chanlist); > > + cmd->chanlist = (unsigned int __force *)compat_ptr(v32.chanlist); > > __force? That feels wrong, something is odd if that is ever needed. > > Are you _sure_ this is correct?
The same file has instances of "(usigned int __force *)" cast being used on the same "cmd->chanlist". For reference:
At line 1797 of comedi_fops.c: 1796 /* restore chanlist pointer before copying back */ 1797 cmd->chanlist = (unsigned int __force *)user_chanlist; 1798 cmd->data = NULL;
At line 1880: 1879 /* restore chanlist pointer before copying back */ 1880 cmd->chanlist = (unsigned int __force *)user_chanlist; 1881 *copy = true;
Here "user_chanlist" is of type "unsigned int __user *".
Or perhaps, I shouldn't be relying on them?
Thanks! Atul
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