From 16c81dd563b94e9392a578ccf5aa762d01e8f165 Mon Sep 17 00:00:00 2001 From: Icenowy Zheng Date: Fri, 28 Oct 2022 16:12:20 +0800 Subject: [PATCH] linux-user: always translate cmsg when recvmsg It's possible that a message contains both normal payload and ancillary data in the same message, and even if no ancillary data is available this information should be passed to the target, otherwise the target cmsghdr will be left uninitialized and the target is going to access uninitialized memory if it expects cmsg. Always call the function that translate cmsg when recvmsg, because that function should be empty-cmsg-safe (it creates an empty cmsg in the target). Signed-off-by: Icenowy Zheng Reviewed-by: Laurent Vivier Message-Id: <20221028081220.1604244-1-uwu@icenowy.me> Signed-off-by: Laurent Vivier --- linux-user/syscall.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 8b18adfba8..24b25759be 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -3353,7 +3353,8 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp, if (fd_trans_host_to_target_data(fd)) { ret = fd_trans_host_to_target_data(fd)(msg.msg_iov->iov_base, MIN(msg.msg_iov->iov_len, len)); - } else { + } + if (!is_error(ret)) { ret = host_to_target_cmsg(msgp, &msg); } if (!is_error(ret)) {