linux-kernel - Re: [PATCH v2] net: Fix uninit character pointer and return values

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Message-ID: <willemdebruijn.kernel.321e70874e73c@gmail.com>
Date: Mon, 29 Sep 2025 13:58:02 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Sidharth Seela <sidharthseela@...il.com>, 
 antonio@...nvpn.net, 
 sd@...asysnail.net, 
 edumazet@...gle.com, 
 kuba@...nel.org, 
 pabeni@...hat.com, 
 horms@...nel.org, 
 shuah@...nel.org, 
 willemdebruijn.kernel@...il.com, 
 kernelxing@...cent.com, 
 nathan@...nel.org, 
 nick.desaulniers+lkml@...il.com, 
 morbo@...gle.com, 
 justinstitt@...gle.com
Cc: netdev@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 llvm@...ts.linux.dev, 
 david.hunter.linux@...il.com, 
 Sidharth Seela <sidharthseela@...il.com>
Subject: Re: [PATCH v2] net: Fix uninit character pointer and return values

Reminder: use the net prefix: [PATCH net v2]

Sidharth Seela wrote:
> Fix uninitialized character pointer, and functions that return
> undefined values. These issues were caught by running clang using LLVM=1
> option; and are as follows:
> --
> ovpn-cli.c:1587:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
>  1587 |         if (!sock) {
>       |             ^~~~~
> ovpn-cli.c:1635:9: note: uninitialized use occurs here
>  1635 |         return ret;
>       |                ^~~
> ovpn-cli.c:1587:2: note: remove the 'if' if its condition is always false
>  1587 |         if (!sock) {
>       |         ^~~~~~~~~~~~
>  1588 |                 fprintf(stderr, "cannot allocate netlink socket\n");
>       |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>  1589 |                 goto err_free;
>       |                 ~~~~~~~~~~~~~~
>  1590 |         }
>       |         ~
> ovpn-cli.c:1584:15: note: initialize the variable 'ret' to silence this warning
>  1584 |         int mcid, ret;
>       |                      ^
>       |                       = 0
> ovpn-cli.c:2107:7: warning: variable 'ret' is used uninitialized whenever switch case is taken [-Wsometimes-uninitialized]
>  2107 |         case CMD_INVALID:
>       |              ^~~~~~~~~~~
> ovpn-cli.c:2111:9: note: uninitialized use occurs here
>  2111 |         return ret;
>       |                ^~~
> ovpn-cli.c:1939:12: note: initialize the variable 'ret' to silence this warning
>  1939 |         int n, ret;
>       |                   ^
>       |
> --
> so_txtime.c:210:3: warning: variable 'reason' is used uninitialized whenever switch default is taken [-Wsometimes-uninitialized]
>   210 |                 default:
>       |                 ^~~~~~~
> so_txtime.c:219:27: note: uninitialized use occurs here
>   219 |                         data[ret - 1], tstamp, reason);
>       |                                                ^~~~~~
> so_txtime.c:177:21: note: initialize the variable 'reason' to silence this warning
>   177 |                 const char *reason;
>       |                                   ^
>       |

My previous response accidentally left a state comment. The main
feedback still held:

This default case calls error() and exits the program, so this cannot
happen.

> --
> Fixes: 959bc330a439 ("testing/selftests: add test tool and scripts for ovpn module")
> ovpn module")
> Fixes: ca8826095e4d4 ("selftests/net: report etf errors correctly")
> 
> Signed-off-by: Sidharth Seela <sidharthseela@...il.com>
> 
> v2:
> 	- Use subsystem name "net".
> 	- Add fixes tags.
> 	- Remove txtimestamp fix as default case calls error.
> 	- Assign constant error string instead of NULL.
> --

End the commit with the Signed-off-by block. Either move changelog
above that, or below three (not two) dashes.
 
> diff --git a/tools/testing/selftests/net/ovpn/ovpn-cli.c b/tools/testing/selftests/net/ovpn/ovpn-cli.c
> index 9201f2905f2c..20d00378f34a 100644
> --- a/tools/testing/selftests/net/ovpn/ovpn-cli.c
> +++ b/tools/testing/selftests/net/ovpn/ovpn-cli.c
> @@ -1581,7 +1581,7 @@ static int ovpn_listen_mcast(void)
>  {
>  	struct nl_sock *sock;
>  	struct nl_cb *cb;
> -	int mcid, ret;
> +	int mcid, ret = -1;
>  
>  	sock = nl_socket_alloc();
>  	if (!sock) {
> @@ -1936,7 +1936,7 @@ static int ovpn_run_cmd(struct ovpn_ctx *ovpn)
>  {
>  	char peer_id[10], vpnip[INET6_ADDRSTRLEN], laddr[128], lport[10];
>  	char raddr[128], rport[10];
> -	int n, ret;
> +	int n, ret = -1;
>  	FILE *fp;
>  
>  	switch (ovpn->cmd) {
> diff --git a/tools/testing/selftests/net/so_txtime.c b/tools/testing/selftests/net/so_txtime.c
> index 8457b7ccbc09..5bf3c483069b 100644
> --- a/tools/testing/selftests/net/so_txtime.c
> +++ b/tools/testing/selftests/net/so_txtime.c
> @@ -174,7 +174,7 @@ static int do_recv_errqueue_timeout(int fdt)
>  	msg.msg_controllen = sizeof(control);
>  
>  	while (1) {
> -		const char *reason;
> +		const char *reason = "unknown errno";
>  
>  		ret = recvmsg(fdt, &msg, MSG_ERRQUEUE);
>  		if (ret == -1 && errno == EAGAIN)
> -- 
> 2.47.3
>