Messages in this thread | | | Date | Mon, 15 Jun 2020 12:42:38 +0300 | From | Andy Shevchenko <> | Subject | Re: [PATCH 1/2] bitmap: Fix bitmap_cut() for partial overlapping case |
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On Sun, Jun 14, 2020 at 07:40:53PM +0200, Stefano Brivio wrote: > Yury Norov reports that bitmap_cut() will not produce the right outcome > if src and dst partially overlap, with src pointing at some location > after dst, because the memmove() affects src before we store the bits > that we need to keep, that is, the bits preceding the cut -- as long as > we the beginning of the cut is not aligned to a long. > > Fix this by storing those bits before the memmove(). > > Note that this is just a theoretical concern so far, as the only user > of this function, pipapo_drop() from the nftables set back-end > implemented in net/netfilter/nft_set_pipapo.c, always supplies entirely > overlapping src and dst.
LGTM as long as test cases are passed, Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reported-by: Yury Norov <yury.norov@gmail.com> > Fixes: 2092767168f0 ("bitmap: Introduce bitmap_cut(): cut bits and shift remaining") > Signed-off-by: Stefano Brivio <sbrivio@redhat.com> > --- > v2: No changes > > lib/bitmap.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/lib/bitmap.c b/lib/bitmap.c > index 89260aa342d6..c5712e8f4c38 100644 > --- a/lib/bitmap.c > +++ b/lib/bitmap.c > @@ -211,13 +211,13 @@ void bitmap_cut(unsigned long *dst, const unsigned long *src, > unsigned long keep = 0, carry; > int i; > > - memmove(dst, src, len * sizeof(*dst)); > - > if (first % BITS_PER_LONG) { > keep = src[first / BITS_PER_LONG] & > (~0UL >> (BITS_PER_LONG - first % BITS_PER_LONG)); > } > > + memmove(dst, src, len * sizeof(*dst)); > + > while (cut--) { > for (i = first / BITS_PER_LONG; i < len; i++) { > if (i < len - 1) > -- > 2.27.0 >
-- With Best Regards, Andy Shevchenko
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