[PATCH] linux-user/syscall: zero-init msghdr in do_sendrecvmsg_locked

[Kenta Iwasaki]

The mixing of libc and kernel versions of the layout of the `msghdr`
struct causes EMSGSIZE to be returned by sendmsg if the `msghdr` struct
is not zero-initialized (such that padding bytes comprise of
uninitialized memory).

Other parts of the QEMU codebase appear to zero-initialize the `msghdr`
struct to workaround these struct layout issues, except for
do_sendrecvmsg_locked in linux-user/syscall.c.

This patch zero-initializes the `msghdr` struct in
do_sendrecvmsg_locked.

Signed-off-by: Kenta Iwasaki <ke...@lithdew.net>
---
 linux-user/syscall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 95d79ddc43..f60b7e04d5 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -3337,7 +3337,7 @@ static abi_long do_sendrecvmsg_locked(int fd, struct 
target_msghdr *msgp,
                                       int flags, int send)
 {
     abi_long ret, len;
-    struct msghdr msg;
+    struct msghdr msg = { 0 };
     abi_ulong count;
     struct iovec *vec;
     abi_ulong target_vec;
-- 
2.31.0