[PATCH] riscv: fix integer wraparound in memcpy

[Kito Cheng]

Hi Chih-Mao:

Thanks for your patch :)

Hi Corinna:

Thanks!

On Mon, Jul 27, 2020 at 4:22 PM Corinna Vinschen via Newlib
<newlib@sourceware.org> wrote:
>
> Hi Chen,
>
> On Jul 24 19:07, PkmX via Newlib wrote:
> > This patch fixes a bug in RISC-V's memcpy implementation where an
> > integer wraparound occurs when src + size < 8 * sizeof(long), causing
> > the word-sized copy loop to be incorrectly entered.
> >
> > Signed-off-by: Chih-Mao Chen <cmchen@andestech.com>
> > ---
> >  newlib/libc/machine/riscv/memcpy.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/newlib/libc/machine/riscv/memcpy.c
> > b/newlib/libc/machine/riscv/memcpy.c
> > index 07e8e0076..4098f3ab1 100644
> > --- a/newlib/libc/machine/riscv/memcpy.c
> > +++ b/newlib/libc/machine/riscv/memcpy.c
> > @@ -51,9 +51,9 @@ small:
> >    const long *lb = (const long *)b;
> >    long *lend = (long *)((uintptr_t)end & ~msk);
> >
> > -  if (unlikely (la < (lend - 8)))
> > +  if (unlikely (lend - la > 8))
> >      {
> > -      while (la < (lend - 8))
> > +      while (lend - la > 8)
> >         {
> >           long b0 = *lb++;
> >           long b1 = *lb++;
> > --
> > 2.27.0
>
> I pushed this, but I had to fix your patch because your MUA broke
> the layout (line breaks, white spaces).
>
> Would you mind to check your MUA settings or send the patch as
> attachment next time?
>
>
> Thanks,
> Corinna
>
> --
> Corinna Vinschen
> Cygwin Maintainer
> Red Hat
>