linux-kernel - [PATCH net-next v4 2/4] netconsole: add support for strings with new line in netpoll_parse_ip

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Message-Id: <20250811-netconsole_ref-v4-2-9c510d8713a2@debian.org>
Date: Mon, 11 Aug 2025 11:13:26 -0700
From: Breno Leitao <leitao@...ian.org>
To: "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
 Breno Leitao <leitao@...ian.org>, Andrew Lunn <andrew+netdev@...n.ch>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 kernel-team@...a.com
Subject: [PATCH net-next v4 2/4] netconsole: add support for strings with
 new line in netpoll_parse_ip_addr

The current IP address parsing logic fails when the input string
contains a trailing newline character. This can occur when IP
addresses are provided through configfs, which contains newlines in
a const buffer.

Teach netpoll_parse_ip_addr() how to ignore newlines at the end of the
IPs. Also, simplify the code by:

 * No need to check for separators. Try to parse ipv4, if it fails try
   ipv6 similarly to ceph_pton()
 * If ipv6 is not supported, don't call in6_pton() at all.

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 drivers/net/netconsole.c | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 8d1b93264e0fd..2919522d963e2 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -300,23 +300,30 @@ static void netconsole_print_banner(struct netpoll *np)
 	np_info(np, "remote ethernet address %pM\n", np->remote_mac);
 }

+/* Parse the string and populate the `inet_addr` union. Return 0 if IPv4 is
+ * populated, 1 if IPv6 is populated, and -1 upon failure.
+ */
 static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr)
 {
-	const char *end;
+	const char *end = NULL;
+	int len;

-	if (!strchr(str, ':') &&
-	    in4_pton(str, -1, (void *)addr, -1, &end) > 0) {
-		if (!*end)
-			return 0;
-	}
-	if (in6_pton(str, -1, addr->in6.s6_addr, -1, &end) > 0) {
-#if IS_ENABLED(CONFIG_IPV6)
-		if (!*end)
-			return 1;
-#else
+	len = strlen(str);
+	if (!len)
 		return -1;
-#endif
-	}
+
+	if (str[len - 1] == '\n')
+		len -= 1;
+
+	if (in4_pton(str, len, (void *)addr, -1, &end) > 0 &&
+	    (!end || *end == 0 || *end == '\n'))
+		return 0;
+
+	if (IS_ENABLED(CONFIG_IPV6) &&
+	    in6_pton(str, len, (void *)addr, -1, &end) > 0 &&
+	    (!end || *end == 0 || *end == '\n'))
+		return 1;
+
 	return -1;
 }

-- 
2.47.3