[PATCH 1/2] drivers/net: udp, packet: Fix returning of msg_namelen and msg_flags from recvmsg

[Jan Kiszka via Xenomai]

From: Jan Kiszka <jan.kis...@siemens.com>

The msg struct passed to the recvmsg handler for udp and packet sockets
is not located in userspace. Therefore, we must not use rtnet_put_arg to
update its content, it may fail on some archs, namely arm and arm64.
Just assign, the syscall entry function will take care of copying it
back.

Fixes: 25a53f5cd352 ("rtnet: udp: Remove duplicate copy_from/to_user")
Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>
---
 kernel/drivers/net/stack/ipv4/udp/udp.c     | 12 ++----------
 kernel/drivers/net/stack/packet/af_packet.c | 13 +++----------
 2 files changed, 5 insertions(+), 20 deletions(-)

diff --git a/kernel/drivers/net/stack/ipv4/udp/udp.c 
b/kernel/drivers/net/stack/ipv4/udp/udp.c
index 6fe1aeb12e..bceb6b5132 100644
--- a/kernel/drivers/net/stack/ipv4/udp/udp.c
+++ b/kernel/drivers/net/stack/ipv4/udp/udp.c
@@ -446,10 +446,7 @@ ssize_t rt_udp_recvmsg(struct rtdm_fd *fd, struct 
user_msghdr *msg,
                        goto fail;
 
                namelen = sizeof(sin);
-               ret = rtnet_put_arg(fd, &msg->msg_namelen, &namelen,
-                                   sizeof(namelen));
-               if (ret)
-                       goto fail;
+               msg->msg_namelen = namelen;
        }
 
        data_len = ntohs(uh->len) - sizeof(struct udphdr);
@@ -489,12 +486,7 @@ ssize_t rt_udp_recvmsg(struct rtdm_fd *fd, struct 
user_msghdr *msg,
        if (data_len > 0)
                flags |= MSG_TRUNC;
 
-       if (flags != msg->msg_flags) {
-               ret = rtnet_put_arg(fd, &msg->msg_flags, &flags,
-                                   sizeof(flags));
-               if (ret)
-                       goto fail;
-       }
+       msg->msg_flags = flags;
 out:
        if ((msg_flags & MSG_PEEK) == 0)
                kfree_rtskb(first_skb);
diff --git a/kernel/drivers/net/stack/packet/af_packet.c 
b/kernel/drivers/net/stack/packet/af_packet.c
index 8a8072c640..0d5ecd6a7d 100644
--- a/kernel/drivers/net/stack/packet/af_packet.c
+++ b/kernel/drivers/net/stack/packet/af_packet.c
@@ -302,7 +302,7 @@ static ssize_t rt_packet_recvmsg(struct rtdm_fd *fd, struct 
user_msghdr *msg,
        size_t copy_len;
        struct rtskb *rtskb;
        struct sockaddr_ll sll;
-       int ret, flags;
+       int ret;
        nanosecs_rel_t timeout = sock->timeout;
        socklen_t namelen;
        struct iovec iov_fast[RTDM_IOV_FASTMAX], *iov;
@@ -355,10 +355,7 @@ static ssize_t rt_packet_recvmsg(struct rtdm_fd *fd, 
struct user_msghdr *msg,
                        goto fail;
 
                namelen = sizeof(sll);
-               ret = rtnet_put_arg(fd, &msg->msg_namelen, &namelen,
-                                   sizeof(namelen));
-               if (ret)
-                       goto fail;
+               msg->msg_namelen = namelen;
        }
 
        /* Include the header in raw delivery */
@@ -375,11 +372,7 @@ static ssize_t rt_packet_recvmsg(struct rtdm_fd *fd, 
struct user_msghdr *msg,
 
        if (copy_len > len) {
                copy_len = len;
-               flags = msg->msg_flags | MSG_TRUNC;
-               ret = rtnet_put_arg(fd, &msg->msg_flags, &flags,
-                                   sizeof(flags));
-               if (ret)
-                       goto fail;
+               msg->msg_flags |= MSG_TRUNC;
        }
 
        copy_len = rtnet_write_to_iov(fd, iov, msg->msg_iovlen, rtskb->data,
-- 
2.31.1