linux-kernel - [PATCH net-next v2 3/8] net: pktgen: fix hex32

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Message-ID: <20250122144110.619989-4-ps.report@gmx.net>
Date: Wed, 22 Jan 2025 15:41:05 +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>,
	Frederic Weisbecker <frederic@...nel.org>,
	Artem Chernyshev <artem.chernyshev@...-soft.ru>,
	Nam Cao <namcao@...utronix.de>,
	Peter Seiderer <ps.report@....net>
Subject: [PATCH net-next v2 3/8] net: pktgen: fix hex32_arg parsing for short reads

Fix hex32_arg parsing for short reads (here 7 hex digits instead of the
expected 8), shift result only on successful input parsing.

- before the patch

	$ echo "mpls 0000123" > /proc/net/pktgen/lo\@0
	$ grep mpls /proc/net/pktgen/lo\@0
	     mpls: 00001230
	Result: OK: mpls=00001230

- with patch applied

	$ echo "mpls 0000123" > /proc/net/pktgen/lo\@0
	$ grep mpls /proc/net/pktgen/lo\@0
	     mpls: 00000123
	Result: OK: mpls=00000123

Signed-off-by: Peter Seiderer <ps.report@....net>
---
Changes v1 -> v2:
  - new patch
---
 net/core/pktgen.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 4f8ec6c9bed4..28dbbf70e142 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -753,14 +753,15 @@ static int hex32_arg(const char __user *user_buffer, unsigned long maxlen,
 	for (; i < maxlen; i++) {
 		int value;
 		char c;
-		*num <<= 4;
 		if (get_user(c, &user_buffer[i]))
 			return -EFAULT;
 		value = hex_to_bin(c);
-		if (value >= 0)
+		if (value >= 0) {
+			*num <<= 4;
 			*num |= value;
-		else
+		} else {
 			break;
+		}
 	}
 	return i;
 }
-- 
2.48.1