linux-kernel - [PATCH net-next v4 12/17] net: pktgen: fix mpls maximum labels list parsing

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Message-ID: <20250205131153.476278-13-ps.report@gmx.net>
Date: Wed,  5 Feb 2025 14:11:48 +0100
From: Peter Seiderer <ps.report@....net>
To: netdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	"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>,
	Shuah Khan <shuah@...nel.org>,
	Peter Seiderer <ps.report@....net>
Subject: [PATCH net-next v4 12/17] net: pktgen: fix mpls maximum labels list parsing

Fix mpls maximum labels list parsing up to MAX_MPLS_LABELS/16 entries
(instead of up to MAX_MPLS_LABELS - 1).

Fixes:

	$ echo "mpls 00000f00,00000f01,00000f02,00000f03,00000f04,00000f05,00000f06,00000f07,00000f08,00000f09,00000f0a,00000f0b,00000f0c,00000f0d,00000f0e,00000f0f" > /proc/net/pktgen/lo\@0
	-bash: echo: write error: Argument list too long

Signed-off-by: Peter Seiderer <ps.report@....net>
---
Changes v3 -> v4
  - new patch (factored out of patch 'net: pktgen: fix access outside of user
    given buffer in pktgen_if_write()')
---
 net/core/pktgen.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 84fd88e48275..0fd15f21119b 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -908,6 +908,10 @@ static int get_labels(const char __user *buffer, struct pktgen_dev *pkt_dev)
 	pkt_dev->nr_labels = 0;
 	do {
 		__u32 tmp;
+
+		if (n >= MAX_MPLS_LABELS)
+			return -E2BIG;
+
 		len = hex32_arg(&buffer[i], HEX_8_DIGITS, &tmp);
 		if (len <= 0)
 			return len;
@@ -919,8 +923,6 @@ static int get_labels(const char __user *buffer, struct pktgen_dev *pkt_dev)
 			return -EFAULT;
 		i++;
 		n++;
-		if (n >= MAX_MPLS_LABELS)
-			return -E2BIG;
 	} while (c == ',');
 
 	pkt_dev->nr_labels = n;
-- 
2.48.1