net: clamp ->msg_namelen instead of returning an error

[ Upstream commit db31c55a6fb245fdbb752a2ca4aefec89afabb06 ]

If kmsg->msg_namelen > sizeof(struct sockaddr_storage) then in the
original code that would lead to memory corruption in the kernel if you
had audit configured.  If you didn't have audit configured it was
harmless.

There are some programs such as beta versions of Ruby which use too
large of a buffer and returning an error code breaks them.  We should
clamp the ->msg_namelen value instead.

Fixes: 1661bf364ae9 ("net: heap overflow in __audit_sockaddr()")
Reported-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Tested-by: Eric Wong <normalperson@yhbt.net>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/compat.c b/net/compat.c
index d325d16f8eaab6282dccb50124baa3afc781abb4..e9672c870427ceba5fc4a2920c70d2f125f04b2e 100644 (file)
--- a/net/compat.c
+++ b/net/compat.c
@@ -70,7 +70,7 @@ int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
            __get_user(kmsg->msg_flags, &umsg->msg_flags))
                return -EFAULT;
        if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
-               return -EINVAL;
+               kmsg->msg_namelen = sizeof(struct sockaddr_storage);
        kmsg->msg_name = compat_ptr(tmp1);
        kmsg->msg_iov = compat_ptr(tmp2);
        kmsg->msg_control = compat_ptr(tmp3);

diff --git a/net/socket.c b/net/socket.c
index 11bad156278414223db184cfa3ba4b45302c46dc..54ac14baa70b45ba4925cbb356d82d513a5b956d 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1872,7 +1872,7 @@ static int copy_msghdr_from_user(struct msghdr *kmsg,
        if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
                return -EFAULT;
        if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
-               return -EINVAL;
+               kmsg->msg_namelen = sizeof(struct sockaddr_storage);
        return 0;
 }