tests: net: socket: socketpair: fails due to empty message header name

[ABOSTM]

Describe the bug
Running test tests/net/socket/socketpair/ fails.

To Reproduce
Steps to reproduce the behavior:

1. west build -p -b nucleo_f429zi tests/net/socket/socketpair/
2. west flash
3. See error

Expected behavior
test passed

Screenshots or console output

Running test suite socketpair
===================================================================
starting test - test_socketpair_AF_LOCAL__SOCK_STREAM__0
E: syscall z_user_alloc_from_copy failed check: Memory region 0x00000000 (size 0) read access denied

    Assertion failed at WEST_TOPDIR/zephyr/tests/net/socket/socketpair/src/test_socketpair_happy_path.c:141: happy_path: (res equal to -1)
sendmsg(2) failed: 12
FAIL - test_socketpair_AF_LOCAL__SOCK_STREAM__0

Analysis
This is a regression introduced with PR #25706
Due to new check on messages parameters, test fails because in function happy_path() ,
msghdr.msg_name is not set and thus equal 0 (and the same for msg_namelen)

But in net_ip.h, in the structure comment, it seems this name is optional:

struct msghdr {
	void         *msg_name;       /* optional socket address */
	socklen_t     msg_namelen;    /* size of socket address */
...

So I don't know whether

• test should be updated and structure comment ?

or

• PR BSD socket sendmsg() parameters were not verified in usermode #25706 should be reworked ?

Note: probably the same will happend with msg_control field of the structure

[ABOSTM]

^^ @jukkar

[jukkar]

* PR #25706 should be reworked ?

As those couple of fields are optional for connected socket, the checks introduced in #25706 need to be fixed. Will send a fix asap.

[jukkar]

I just wonder why this issue was not caught by sanitychecker.