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: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 9d18326..51f558d 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -3472,7 +3472,14 @@
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 @@
}
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) {
