[PATCH v12 08/13] net, arm64: untag user pointers in tcp_zerocopy_receive
From: Andrey Konovalov
Date: Mon Mar 18 2019 - 13:19:08 EST
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 | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 6baa6dc1b13b..e76beb5ff1ff 100644
@@ -1749,7 +1749,7 @@ EXPORT_SYMBOL(tcp_mmap);
static int tcp_zerocopy_receive(struct sock *sk,
struct tcp_zerocopy_receive *zc)
- unsigned long address = (unsigned long)zc->address;
+ unsigned long address;
const skb_frag_t *frags = NULL;
u32 length = 0, seq, offset;
struct vm_area_struct *vma;
@@ -1758,7 +1758,12 @@ static int tcp_zerocopy_receive(struct sock *sk,
- if (address & (PAGE_SIZE - 1) || address != zc->address)
+ address = (unsigned long)untagged_addr(zc->address);
+ /* The second test in this if detects if the u64->unsigned long
+ * conversion had any truncated bits.
+ if (address & (PAGE_SIZE - 1) || address != untagged_addr(zc->address))
if (sk->sk_state == TCP_LISTEN)