[PATCH v13 09/20] net, arm64: untag user pointers in tcp_zerocopy_receive

[Andrey Konovalov]

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 at google.com>
---
 net/ipv4/tcp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 6baa6dc1b13b..855a1f68c1ea 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1761,6 +1761,8 @@ static int tcp_zerocopy_receive(struct sock *sk,
 	if (address & (PAGE_SIZE - 1) || address != zc->address)
 		return -EINVAL;
 
+	address = untagged_addr(address);
+
 	if (sk->sk_state == TCP_LISTEN)
 		return -ENOTCONN;
 
-- 
2.21.0.225.g810b269d1ac-goog