[PATCH v11 08/14] net, arm64: untag user pointers in tcp_zerocopy_receive

Andrey Konovalov andreyknvl at google.com
Fri Mar 15 12:51:32 PDT 2019

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..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)
 		return -EINVAL;

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