Re: [PATCH v11 08/14] net, arm64: untag user pointers in tcp_zerocopy_receive
From: Eric Dumazet <hidden>
Date: 2019-03-15 20:03:37
Also in:
bpf, linux-arch, linux-arm-kernel, linux-doc, linux-kselftest, linux-mm, lkml
On 03/15/2019 12:51 PM, Andrey Konovalov wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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
return -EINVAL;