On Mon, Mar 18, 2019 at 2:14 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: > > On Fri, Mar 15, 2019 at 9:03 PM Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote: > > > > > > > > On 03/15/2019 12:51 PM, Andrey Konovalov wrote: > > > This patch is a part of a series that extends arm64 kernel ABI to allow to > > > pass tagged user pointers (with the top byte set to something else other > > > than 0x00) as syscall arguments. > > > > > > tcp_zerocopy_receive() uses provided user pointers for vma lookups, which > > > can only by done with untagged pointers. > > > > > > Untag user pointers in this function. > > > > > > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > > > --- > > > net/ipv4/tcp.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > > > index 6baa6dc1b13b..89db3b4fc753 100644 > > > --- a/net/ipv4/tcp.c > > > +++ b/net/ipv4/tcp.c > > > @@ -1758,6 +1758,8 @@ static int tcp_zerocopy_receive(struct sock *sk, > > > int inq; > > > int ret; > > > > > > + address = untagged_addr(address); > > > + > > > if (address & (PAGE_SIZE - 1) || address != zc->address) > > > > The second test will fail, if the top bits are changed in address but not in zc->address > > Will fix in v12, thanks Eric! Looking at the code, what's the point of this address != zc->address check? Should I just remove it? > > > > > > return -EINVAL; > > > > > > > >
