Hi Srinivas,
Thanks for the feedback.
> Subject: Re: [PATCH v4 1/5] nvmem: check invalid number of bytes in
> nvmem_device_{read,write}
>
> Thanks for the patch.
>
> On 07/12/18 11:27, Biju Das wrote:
> > Add check in nvmem_device_{read,write}()to ensure that nvmem core
> > never passes an invalid number of bytes.
> >
> > Signed-off-by: Biju Das <biju.das@xxxxxxxxxxxxxx>
> > ---
> > V3-->V4
> > * New patch.
> > ---
> > drivers/nvmem/core.c | 26 +++++++++++++++++++++++++-
> > 1 file changed, 25 insertions(+), 1 deletion(-)
> >
>
> Its better to move checks from
> bin_attr_nvmem_read()/bin_attr_nvmem_write() into nvmem_reg_read()
> and nvmem_reg_write(), so its easy to maintain, rather than adding them to
> each function.
Initially I also thought the same. But there are some RTC drivers which is using nvmem_device
interface is not defining "word_size" member. That is the reason we need to add it in separate function.
Can you please suggest how to handle the above drivers?
> > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index
> > d9fd110..db7de33 100644
> > --- a/drivers/nvmem/core.c
> > +++ b/drivers/nvmem/core.c
> > @@ -1433,10 +1433,21 @@ int nvmem_device_read(struct nvmem_device
> *nvmem,
> > size_t bytes, void *buf)
> > {
> > int rc;
> > +size_t new_bytes;
> >
> > if (!nvmem)
> > return -EINVAL;
> >
> > +/* Stop the user from reading */
> > +if ((offset >= nvmem->size) || (bytes == 0))
> > +return 0;
> > +
> > +if (unlikely(check_add_overflow(bytes, offset, &new_bytes)))
> > +return -EOVERFLOW;
> > +
> > +if (new_bytes > nvmem->size)
> > +bytes = nvmem->size - offset;
> > +
> > rc = nvmem_reg_read(nvmem, offset, buf, bytes);
> >
> > if (rc)
> > @@ -1461,16 +1472,29 @@ int nvmem_device_write(struct
> nvmem_device *nvmem,
> > size_t bytes, void *buf)
> > {
> > int rc;
> > +size_t new_bytes;
> >
> > if (!nvmem)
> > return -EINVAL;
> >
> > +/* Stop the user from writing */
> > +if (offset >= nvmem->size)
> > +return -ENOSPC;
> > +
> > +if (bytes == 0)
> > +return 0;
> > +
> > +if (unlikely(check_add_overflow(bytes, offset, &new_bytes)))
> > +return -EOVERFLOW;
> > +
> > +if (new_bytes > nvmem->size)
> > +bytes = nvmem->size - offset;
> > +
> > rc = nvmem_reg_write(nvmem, offset, buf, bytes);
> >
> > if (rc)
> > return rc;
> >
> > -
>
> Unrelated change!
I found an extra space in this function. If it is a problem, I will send V2 for undoing this.
Please let me know.
Regards,
Biju
[https://www2.renesas.eu/media/email/unicef.jpg]
This Christmas, instead of sending out cards, Renesas Electronics Europe have decided to support Unicef with a donation. For further details click here<https://www.unicef.org/> to find out about the valuable work they do, helping children all over the world.
We would like to take this opportunity to wish you a Merry Christmas and a prosperous New Year.
Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered No. 04586709.
