selftests/net: fix a char signedness issue

Signedness of char is signed on x86_64, but unsigned on arm64.

Fix the warning building cmsg_sender.c on signed platforms or
forced with -fsigned-char:

    msg_sender.c:455:12:
    error: implicit conversion from 'int' to 'char'
    changes value from 128 to -128
    [-Werror,-Wconstant-conversion]
        buf[0] = ICMPV6_ECHO_REQUEST;

constant ICMPV6_ECHO_REQUEST is 128.

Link: https://lwn.net/Articles/911914
Fixes: de17e305a810 ("selftests: net: cmsg_sender: support icmp and raw sockets")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20231124171645.1011043-3-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/selftests/net/cmsg_sender.c b/tools/testing/selftests/net/cmsg_sender.c
index 24b21b15ed3fb05ba677328c4d68a258d9819169..6ff3e732f449f949add1bae24657c31e8dba493f 100644 (file)
--- a/tools/testing/selftests/net/cmsg_sender.c
+++ b/tools/testing/selftests/net/cmsg_sender.c
@@ -416,9 +416,9 @@ int main(int argc, char *argv[])
 {
        struct addrinfo hints, *ai;
        struct iovec iov[1];
+       unsigned char *buf;
        struct msghdr msg;
        char cbuf[1024];
-       char *buf;
        int err;
        int fd;