Commit 26a6fc96 authored by Peter Maydell's avatar Peter Maydell Committed by Riku Voipio
Browse files

linux-user: Allow bad msg_name for recvfrom on connected socket 



The POSIX standard mandates that for a connected socket recvfrom()
must ignore the msg_name and msg_namelen fields. This is awkward
for QEMU because we will attempt to copy them from guest address
space. Handle this by not immediately returning a TARGET_EFAULT
if the copy failed, but instead passing a known-bad address
to the host kernel, which can then return EFAULT or ignore the
value appropriately.

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: default avatarRiku Voipio <riku.voipio@linaro.org>
parent 97b07970

linux-user/syscall.c

+9 −2
Original line number Diff line number Diff line
@@ -3472,7 +3472,14 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp, 
        ret = target_to_host_sockaddr(fd, msg.msg_name,

                                      tswapal(msgp->msg_name),

                                      msg.msg_namelen);

        if (ret) {

        if (ret == -TARGET_EFAULT) {

            /* For connected sockets msg_name and msg_namelen must

             * be ignored, so returning EFAULT immediately is wrong.

             * Instead, pass a bad msg_name to the host kernel, and

             * let it decide whether to return EFAULT or not.

             */

            msg.msg_name = (void *)-1;

        } else if (ret) {

            goto out2;

        }

    } else {
@@ -3534,7 +3541,7 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp, 
            }

            if (!is_error(ret)) {

                msgp->msg_namelen = tswap32(msg.msg_namelen);

                if (msg.msg_name != NULL) {

                if (msg.msg_name != NULL && msg.msg_name != (void *)-1) {

                    ret = host_to_target_sockaddr(tswapal(msgp->msg_name),

                                    msg.msg_name, msg.msg_namelen);

                    if (ret) {