On Fri, Jan 26, 2024 at 08:31:04PM +0100, Eugenio Perez Martin wrote: > On Tue, Jan 23, 2024 at 2:42 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > > In an effort to separate intentional arithmetic wrap-around from > > unexpected wrap-around, we need to refactor places that depend on this > > kind of math. One of the most common code patterns of this is: > > > > VAR + value < VAR > > > > Notably, this is considered "undefined behavior" for signed and pointer > > types, which the kernel works around by using the -fno-strict-overflow > > option in the build[1] (which used to just be -fwrapv). Regardless, we > > want to get the kernel source to the position where we can meaningfully > > instrument arithmetic wrap-around conditions and catch them when they > > are unexpected, regardless of whether they are signed[2], unsigned[3], > > or pointer[4] types. > > > > Refactor open-coded unsigned wrap-around addition test to use > > check_add_overflow(), retaining the result for later usage (which removes > > the redundant open-coded addition). This paves the way to enabling the > > unsigned wrap-around sanitizer[2] in the future. > > > > Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1] > > Link: https://github.com/KSPP/linux/issues/26 [2] > > Link: https://github.com/KSPP/linux/issues/27 [3] > > Link: https://github.com/KSPP/linux/issues/344 [4] > > Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx> > > Cc: Jason Wang <jasowang@xxxxxxxxxx> > > Cc: kvm@xxxxxxxxxxxxxxx > > Cc: virtualization@xxxxxxxxxxxxxxx > > Cc: netdev@xxxxxxxxxxxxxxx > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > --- > > drivers/vhost/vringh.c | 8 +++++--- > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c > > index 7b8fd977f71c..07442f0a52bd 100644 > > --- a/drivers/vhost/vringh.c > > +++ b/drivers/vhost/vringh.c > > @@ -145,6 +145,8 @@ static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len, > > bool (*getrange)(struct vringh *, > > u64, struct vringh_range *)) > > { > > + u64 sum; > > I understand this is part of a bulk change so little time to think > about names :). But what about "end" or similar? > > Either way, > Acked-by: Eugenio Pérez <eperezma@xxxxxxxxxx> Thanks! Yeah, you are not alone in suggesting "end" in a several of these patches. :) -Kees -- Kees Cook
