[PATCH] sock_diag.7: Fix recvmsg() usage in the example
From: Alejandro Colomar <hidden>
Date: 2021-01-24 15:13:53
Subsystem:
the rest · Maintainer:
Linus Torvalds
From: Pali Rohár <pali@kernel.org> The msg_name field for recvmsg() call points to a caller-allocated buffer nladdr that is used to return the source address of the (netlink) socket. As recvmsg() does not read this buffer and fills it for a caller, do not initialize it and instead check its value in the example. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Alejandro Colomar <redacted> --- man7/sock_diag.7 | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/man7/sock_diag.7 b/man7/sock_diag.7
index b732b2571..569106dd6 100644
--- a/man7/sock_diag.7
+++ b/man7/sock_diag.7@@ -753,9 +753,7 @@ static int receive_responses(int fd) { long buf[8192 / sizeof(long)]; - struct sockaddr_nl nladdr = { - .nl_family = AF_NETLINK - }; + struct sockaddr_nl nladdr; struct iovec iov = { .iov_base = buf, .iov_len = sizeof(buf)
@@ -782,6 +780,11 @@ receive_responses(int fd) if (ret == 0) return 0; + if (nladdr.nl_family != AF_NETLINK) { + fputs("!AF_NETLINK\en", stderr); + return \-1; + } + const struct nlmsghdr *h = (struct nlmsghdr *) buf; if (!NLMSG_OK(h, ret)) {
--
2.30.0