Re: [PATCH v3] misc: fastrpc: fix improper packet size calculation

[jeyr]

On 2021-11-19 18:23, Greg KH wrote:
> On Fri, Nov 19, 2021 at 06:19:27PM +0530, jeyr@xxxxxxxxxxxxxx wrote:
> > On 2021-09-21 18:43, jeyr@xxxxxxxxxxxxxx wrote:
> > > On 2021-09-21 18:10, Greg KH wrote:
> > > > On Tue, Sep 21, 2021 at 06:03:42PM +0530, jeyr@xxxxxxxxxxxxxx wrote:
> > > > > On 2021-09-21 17:22, Greg KH wrote:
> > > > > > On Tue, Sep 21, 2021 at 05:18:15PM +0530, Jeya R wrote:
> > > > > > > The buffer list is sorted and this is not being considered while
> > > > > > > calculating packet size. This would lead to improper copy length
> > > > > > > calculation for non-dmaheap buffers which would eventually cause
> > > > > > > sending improper buffers to DSP.
> > > > > > >
> > > > > > > Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke
> > > > > > > method")
> > > > > > > Signed-off-by: Jeya R <jeyr@xxxxxxxxxxxxxx>
> > > > > > > Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> > > > > >
> > > > > > Does this also need to go to the stable kernels?
> > > > > Yes, this needs to go to stable kernels also as this fixes a
> > > > > potential issue
> > > > > which is easily reproducible.
> > > >
> > > >
> > > >
> > > > >
> > > > > >
> > > > > > > ---
> > > > > > > Changes in v3:
> > > > > > > - relocate patch change list
> > > > > > >
> > > > > > > Changes in v2:
> > > > > > > - updated commit message to proper format
> > > > > > > - added fixes tag to commit message
> > > > > > > - removed unnecessary variable initialization
> > > > > > > - removed length check during payload calculation
> > > > > > >
> > > > > > >  drivers/misc/fastrpc.c | 10 ++++++----
> > > > > > >  1 file changed, 6 insertions(+), 4 deletions(-)
> > > > > > >
> > > > > > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> > > > > > > index beda610..69d45c4 100644
> > > > > > > --- a/drivers/misc/fastrpc.c
> > > > > > > +++ b/drivers/misc/fastrpc.c
> > > > > > > @@ -719,16 +719,18 @@ static int fastrpc_get_meta_size(struct
> > > > > > > fastrpc_invoke_ctx *ctx)
> > > > > > >  static u64 fastrpc_get_payload_size(struct fastrpc_invoke_ctx *ctx,
> > > > > > > int metalen)
> > > > > > >  {
> > > > > > >  	u64 size = 0;
> > > > > > > -	int i;
> > > > > > > +	int oix;
> > > > > >
> > > > > > What does "oix" stand for?  What was wrong with i?
> > > > > It is just a general convention we use. "oix" is used to iterate
> > > > > through
> > > > > sorted overlap buffer list and use "i" to get corresponding
> > > > > unsorted list
> > > > > index. We follow the same convention at other places also, for
> > > > > example:
> > > > > fastrpc_get_args function.
> > > >
> > > > That is the only place it is used in all of the whole kernel tree.  It
> > > > is not a normal variable for a loop, so who is "we" here?
> > > The convention was followed for the same file(fastrpc.c). As part of
> > > fastrpc_get_args
> > > function, while iterating through sorted buffer list, oix is used as
> > > index and to
> > > get unsorted index "raix", it is using "i". Just following the same way
> > > here to
> > > have better understanding. Please let me know if this is a concern, it
> > > can be updated
> > > to "i", "j" etc.
> > >
> > > -- Thanks
> > > >
> > > > thanks,
> > > >
> > > > greg k-h
> > Hello Greg,
> >
> > Is this bug-fix patch planned to be released?
>
> Released in what way?
By release, I mean picked to your misc driver git tree.
> I do not see it in any tree anywhere, perhaps it needs to be 
> resubmitted
> to be accepted?
Sure, will resubmit the patch. Thanks.
> thanks,
>
> greg k-h