* [PATCH] sock_diag.7: Fix recvmsg() usage in the example
@ 2021-01-16 18:45 Pali Rohár
2021-01-17 16:08 ` Alejandro Colomar (man-pages)
0 siblings, 1 reply; 4+ messages in thread
From: Pali Rohár @ 2021-01-16 18:45 UTC (permalink / raw)
To: linux-man, Alejandro Colomar, Michael Kerrisk
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>
---
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 91ccf3ac5..191e6ac49 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)) {
--
2.20.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] sock_diag.7: Fix recvmsg() usage in the example
2021-01-16 18:45 [PATCH] sock_diag.7: Fix recvmsg() usage in the example Pali Rohár
@ 2021-01-17 16:08 ` Alejandro Colomar (man-pages)
0 siblings, 0 replies; 4+ messages in thread
From: Alejandro Colomar (man-pages) @ 2021-01-17 16:08 UTC (permalink / raw)
To: Pali Rohár, Michael Kerrisk; +Cc: linux-man
On 1/16/21 7:45 PM, Pali Rohár wrote:
> 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>
Hi Pali,
Patch applied.
Thanks,
Alex
> ---
> 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 91ccf3ac5..191e6ac49 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)) {
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] sock_diag.7: Fix recvmsg() usage in the example
@ 2021-01-24 15:10 Alejandro Colomar
2021-01-25 7:02 ` Michael Kerrisk (man-pages)
0 siblings, 1 reply; 4+ messages in thread
From: Alejandro Colomar @ 2021-01-24 15:10 UTC (permalink / raw)
To: mtk.manpages; +Cc: linux-man, Pali Rohár, Alejandro Colomar
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 <alx.manpages@gmail.com>
---
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
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] sock_diag.7: Fix recvmsg() usage in the example
2021-01-24 15:10 Alejandro Colomar
@ 2021-01-25 7:02 ` Michael Kerrisk (man-pages)
0 siblings, 0 replies; 4+ messages in thread
From: Michael Kerrisk (man-pages) @ 2021-01-25 7:02 UTC (permalink / raw)
To: Alejandro Colomar; +Cc: mtk.manpages, linux-man, Pali Rohár
On 1/24/21 4:10 PM, Alejandro Colomar wrote:
> 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 <alx.manpages@gmail.com>
Hello Alex, Pali,
Thanks. Patch applied.
Cheers,
Michael
> ---
> 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)) {
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-01-16 18:45 [PATCH] sock_diag.7: Fix recvmsg() usage in the example Pali Rohár
2021-01-17 16:08 ` Alejandro Colomar (man-pages)
2021-01-24 15:10 Alejandro Colomar
2021-01-25 7:02 ` Michael Kerrisk (man-pages)
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