[U-Boot] [PATCH v3] arm: socfpga: mailbox: Fix off-by-one error on command length checking

[Simon Goldschmidt]

Marek Vasut <marex at denx.de> schrieb am Fr., 19. Apr. 2019, 11:29:

> On 4/19/19 8:17 AM, Ley Foon Tan wrote:
> > A mailbox command contains 1-DWORD header + arguments. The "len" variable
> > only contains the length of the arguments, but not the 1-DWORD header.
> > Include the length of header when checking the ring buffer space to
> > prevent off-by-one error.
>
> How long is a DWORD ? Windows API (which we have nothing to do with)
> defines that as 32bit type, "typedef unsigned long DWORD;", see [1].
> But the patch below fixes an off-by-one error , not off by four error ?
>

As all the macros for that mailbox seem to do u32 index access only, I'd be
ok with the commit message if it didn't use the term 'DWORD'...

Regards,
Simon


> [1]
> https://docs.microsoft.com/en-us/windows/desktop/winprog/windows-data-types
>
> > Signed-off-by: Ley Foon Tan <ley.foon.tan at intel.com>
> > Signed-off-by: Chee Hong Ang <chee.hong.ang at intel.com>
> > ---
> > v2->v3:
> > - Update commit description.
> > ---
> >  arch/arm/mach-socfpga/mailbox_s10.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/mach-socfpga/mailbox_s10.c
> b/arch/arm/mach-socfpga/mailbox_s10.c
> > index 3c33223936..8363c93e90 100644
> > --- a/arch/arm/mach-socfpga/mailbox_s10.c
> > +++ b/arch/arm/mach-socfpga/mailbox_s10.c
> > @@ -59,7 +59,7 @@ static __always_inline int
> mbox_fill_cmd_circular_buff(u32 header, u32 len,
> >        */
> >       if (((cin + 1) % MBOX_CMD_BUFFER_SIZE) == cout ||
> >           ((MBOX_CMD_BUFFER_SIZE - cin + cout - 1) %
> > -          MBOX_CMD_BUFFER_SIZE) < len)
> > +          MBOX_CMD_BUFFER_SIZE) < (len + 1))
> >               return -ENOMEM;
> >
> >       /* write header to circular buffer */
> >
>
>
> --
> Best regards,
> Marek Vasut
>