socket: fix AF_PACKET recvmsg() and sockaddr formatting

 - Do not unconditionally pass the `MSG_CMSG_CLOEXEC` flag to `recvmsg()`
   invocations as not all protocol specific recvmsg implementations in the
   kernel tolerate it; `packet_recvmsg()` for example will immediately
   return yield `EINVAL` if any non-whitelisted flag is passed.

 - Ensure that the HW address string buffer is zero-terminated when
   converting MAC addresses from C to ucode values.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 5 insertions, 6 deletions

diff --git a/lib/socket.c b/lib/socket.c
index db77188..c91898a 100644
--- a/lib/socket.c
+++ b/lib/socket.c
@@ -306,13 +306,16 @@ hwaddr_to_uv(uint8_t *addr, size_t alen)
 	char buf[sizeof("FF:FF:FF:FF:FF:FF:FF:FF")], *p = buf;
 	const char *hex = "0123456789ABCDEF";
 
-	for (size_t i = 0; i < alen && i < 8; i++) {
+	if (alen > 8)
+		alen = 8;
+
+	for (size_t i = 0; i < alen; i++) {
 		if (i) *p++ = ':';
 		*p++ = hex[addr[i] / 16];
 		*p++ = hex[addr[i] % 16];
 	}
 
-	return ucv_string_new(buf);
+	return ucv_string_new_length(buf, alen);
 }
 
 static bool
@@ -3920,10 +3923,6 @@ uc_socket_inst_recvmsg(uc_vm_t *vm, size_t nargs)
 
 	flagval = flags ? ucv_int64_get(flags) : 0;
 
-#if defined(__linux__)
-	flagval |= MSG_CMSG_CLOEXEC;
-#endif
-
 	/* prepare ancillary data buffer */
 	if (anclength) {
 		size_t sz = ucv_to_unsigned(anclength);