Message-ID: <20250205131153.476278-14-ps.report@gmx.net>
Date: Wed,  5 Feb 2025 14:11:49 +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 13/17] net: pktgen: fix access outside of user given buffer in pktgen_if_write()

Honour the user given buffer size for the hex32_arg(), num_arg(),
strn_len(), get_imix_entries() and get_labels() calls (otherwise they will
access memory outside of the user given buffer).

Signed-off-by: Peter Seiderer <ps.report@....net>
---
Changes v3 -> v4:
  - replace C99 comment (suggested by Paolo Abeni)
  - drop available characters check in strn_len() (suggested by Paolo Abeni)
  - factored out patch 'net: pktgen: align some variable declarations to the
    most common pattern' (suggested by Paolo Abeni)
  - factored out patch 'net: pktgen: remove extra tmp variable (re-use len
    instead)' (suggested by Paolo Abeni)
  - factored out patch 'net: pktgen: remove some superfluous variable
    initializing' (suggested by Paolo Abeni)
  - factored out patch 'net: pktgen: fix mpls maximum labels list parsing'
    (suggested by Paolo Abeni)
  - factored out 'net: pktgen: hex32_arg/num_arg error out in case no
    characters are available' (suggested by Paolo Abeni)
  - factored out 'net: pktgen: num_arg error out in case no valid character
    is parsed' (suggested by Paolo Abeni)

Changes v2 -> v3:
  - no changes

Changes v1 -> v2:
  - additional fix get_imix_entries() and get_labels()
---
 net/core/pktgen.c | 176 ++++++++++++++++++++++++++++++----------------
 1 file changed, 117 insertions(+), 59 deletions(-)

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 0fd15f21119b..3c42ecf17ba2 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -851,10 +851,11 @@ static int strn_len(const char __user * user_buffer, unsigned int maxlen)
  * "size1,weight_1 size2,weight_2 ... size_n,weight_n" for example.
  */
 static int get_imix_entries(const char __user *buffer,
+			    unsigned int maxlen,
 			    struct pktgen_dev *pkt_dev)
 {
 	char c;
-	int i = 0, len;
+	int i = 0, max, len;
 
 	pkt_dev->n_imix_entries = 0;
 
@@ -865,10 +866,13 @@ static int get_imix_entries(const char __user *buffer,
 		if (pkt_dev->n_imix_entries >= MAX_IMIX_ENTRIES)
 			return -E2BIG;
 
-		len = num_arg(&buffer[i], DEC_10_DIGITS, &size);
+		max = min(DEC_10_DIGITS, maxlen - i);
+		len = num_arg(&buffer[i], max, &size);
 		if (len < 0)
 			return len;
 		i += len;
+		if (i >= maxlen)
+			return -EINVAL;
 		if (get_user(c, &buffer[i]))
 			return -EFAULT;
 		/* Check for comma between size_i and weight_i */
@@ -879,7 +883,8 @@ static int get_imix_entries(const char __user *buffer,
 		if (size < 14 + 20 + 8)
 			size = 14 + 20 + 8;
 
-		len = num_arg(&buffer[i], DEC_10_DIGITS, &weight);
+		max = min(DEC_10_DIGITS, maxlen - i);
+		len = num_arg(&buffer[i], max, &weight);
 		if (len < 0)
 			return len;
 		if (weight <= 0)
@@ -889,21 +894,23 @@ static int get_imix_entries(const char __user *buffer,
 		pkt_dev->imix_entries[pkt_dev->n_imix_entries].weight = weight;
 
 		i += len;
+		pkt_dev->n_imix_entries++;
+
+		if (i >= maxlen)
+			break;
 		if (get_user(c, &buffer[i]))
 			return -EFAULT;
-
 		i++;
-		pkt_dev->n_imix_entries++;
 	} while (c == ' ');
 
 	return i;
 }
 
-static int get_labels(const char __user *buffer, struct pktgen_dev *pkt_dev)
+static int get_labels(const char __user *buffer, int maxlen, struct pktgen_dev *pkt_dev)
 {
 	char c;
-	int i = 0, len;
 	unsigned int n = 0;
+	int i = 0, max, len;
 
 	pkt_dev->nr_labels = 0;
 	do {
@@ -912,17 +919,20 @@ static int get_labels(const char __user *buffer, struct pktgen_dev *pkt_dev)
 		if (n >= MAX_MPLS_LABELS)
 			return -E2BIG;
 
-		len = hex32_arg(&buffer[i], HEX_8_DIGITS, &tmp);
+		max = min(HEX_8_DIGITS, maxlen - i);
+		len = hex32_arg(&buffer[i], max, &tmp);
 		if (len <= 0)
 			return len;
 		pkt_dev->labels[n] = htonl(tmp);
 		if (pkt_dev->labels[n] & MPLS_STACK_BOTTOM)
 			pkt_dev->flags |= F_MPLS_RND;
 		i += len;
+		n++;
+		if (i >= maxlen)
+			break;
 		if (get_user(c, &buffer[i]))
 			return -EFAULT;
 		i++;
-		n++;
 	} while (c == ',');
 
 	pkt_dev->nr_labels = n;
@@ -986,8 +996,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	i = len;
 
 	/* Read variable name */
-
-	len = strn_len(&user_buffer[i], sizeof(name) - 1);
+	max = min(sizeof(name) - 1, count - i);
+	len = strn_len(&user_buffer[i], max);
 	if (len < 0)
 		return len;
 
@@ -1015,7 +1025,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "min_pkt_size")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1032,7 +1043,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "max_pkt_size")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1051,7 +1063,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	/* Shortcut for min = max */
 
 	if (!strcmp(name, "pkt_size")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1071,7 +1084,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		if (pkt_dev->clone_skb > 0)
 			return -EINVAL;
 
-		len = get_imix_entries(&user_buffer[i], pkt_dev);
+		max = count - i;
+		len = get_imix_entries(&user_buffer[i], max, pkt_dev);
 		if (len < 0)
 			return len;
 
@@ -1082,7 +1096,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "debug")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1093,7 +1108,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "frags")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1103,7 +1119,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "delay")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1118,7 +1135,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "rate")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1133,7 +1151,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "ratep")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1148,7 +1167,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "udp_src_min")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1161,7 +1181,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "udp_dst_min")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1174,7 +1195,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "udp_src_max")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1187,7 +1209,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "udp_dst_max")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1200,7 +1223,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "clone_skb")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 		/* clone_skb is not supported for netif_receive xmit_mode and
@@ -1221,7 +1245,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "count")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1232,7 +1257,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "src_mac_count")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1246,7 +1272,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "dst_mac_count")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1260,7 +1287,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "burst")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1279,7 +1307,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "node")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1300,11 +1329,12 @@ static ssize_t pktgen_if_write(struct file *file,
 	if (!strcmp(name, "xmit_mode")) {
 		char f[32];
 
-		memset(f, 0, 32);
-		len = strn_len(&user_buffer[i], sizeof(f) - 1);
+		max = min(sizeof(f) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
+		memset(f, 0, sizeof(f));
 		if (copy_from_user(f, &user_buffer[i], len))
 			return -EFAULT;
 		i += len;
@@ -1340,11 +1370,12 @@ static ssize_t pktgen_if_write(struct file *file,
 		char f[32];
 		char *end;
 
-		memset(f, 0, 32);
-		len = strn_len(&user_buffer[i], sizeof(f) - 1);
+		max = min(sizeof(f) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
+		memset(f, 0, 32);
 		if (copy_from_user(f, &user_buffer[i], len))
 			return -EFAULT;
 		i += len;
@@ -1389,7 +1420,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "dst_min") || !strcmp(name, "dst")) {
-		len = strn_len(&user_buffer[i], sizeof(pkt_dev->dst_min) - 1);
+		max = min(sizeof(pkt_dev->dst_min) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
@@ -1409,7 +1441,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "dst_max")) {
-		len = strn_len(&user_buffer[i], sizeof(pkt_dev->dst_max) - 1);
+		max = min(sizeof(pkt_dev->dst_max) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
@@ -1429,7 +1462,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "dst6")) {
-		len = strn_len(&user_buffer[i], sizeof(buf) - 1);
+		max = min(sizeof(buf) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
@@ -1452,7 +1486,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "dst6_min")) {
-		len = strn_len(&user_buffer[i], sizeof(buf) - 1);
+		max = min(sizeof(buf) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
@@ -1474,7 +1509,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "dst6_max")) {
-		len = strn_len(&user_buffer[i], sizeof(buf) - 1);
+		max = min(sizeof(buf) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
@@ -1495,7 +1531,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "src6")) {
-		len = strn_len(&user_buffer[i], sizeof(buf) - 1);
+		max = min(sizeof(buf) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
@@ -1518,7 +1555,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "src_min")) {
-		len = strn_len(&user_buffer[i], sizeof(pkt_dev->src_min) - 1);
+		max = min(sizeof(pkt_dev->src_min) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
@@ -1538,7 +1576,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "src_max")) {
-		len = strn_len(&user_buffer[i], sizeof(pkt_dev->src_max) - 1);
+		max = min(sizeof(pkt_dev->src_max) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
@@ -1558,7 +1597,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "dst_mac")) {
-		len = strn_len(&user_buffer[i], sizeof(valstr) - 1);
+		max = min(sizeof(valstr) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
@@ -1575,7 +1615,8 @@ static ssize_t pktgen_if_write(struct file *file,
 		return count;
 	}
 	if (!strcmp(name, "src_mac")) {
-		len = strn_len(&user_buffer[i], sizeof(valstr) - 1);
+		max = min(sizeof(valstr) - 1, count - i);
+		len = strn_len(&user_buffer[i], max);
 		if (len < 0)
 			return len;
 
@@ -1599,7 +1640,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "flows")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1613,7 +1655,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 #ifdef CONFIG_XFRM
 	if (!strcmp(name, "spi")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1624,7 +1667,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 #endif
 	if (!strcmp(name, "flowlen")) {
-		len = num_arg(&user_buffer[i], DEC_10_DIGITS, &value);
+		max = min(DEC_10_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1635,7 +1679,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "queue_map_min")) {
-		len = num_arg(&user_buffer[i], DEC_5_DIGITS, &value);
+		max = min(DEC_5_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1646,7 +1691,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "queue_map_max")) {
-		len = num_arg(&user_buffer[i], DEC_5_DIGITS, &value);
+		max = min(DEC_5_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1659,7 +1705,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	if (!strcmp(name, "mpls")) {
 		unsigned int n, cnt;
 
-		len = get_labels(&user_buffer[i], pkt_dev);
+		max = count - i;
+		len = get_labels(&user_buffer[i], max, pkt_dev);
 		if (len < 0)
 			return len;
 		i += len;
@@ -1680,7 +1727,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "vlan_id")) {
-		len = num_arg(&user_buffer[i], DEC_4_DIGITS, &value);
+		max = min(DEC_4_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1707,7 +1755,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "vlan_p")) {
-		len = num_arg(&user_buffer[i], DEC_1_DIGITS, &value);
+		max = min(DEC_1_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1722,7 +1771,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "vlan_cfi")) {
-		len = num_arg(&user_buffer[i], DEC_1_DIGITS, &value);
+		max = min(DEC_1_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1737,7 +1787,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "svlan_id")) {
-		len = num_arg(&user_buffer[i], DEC_4_DIGITS, &value);
+		max = min(DEC_4_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1764,7 +1815,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "svlan_p")) {
-		len = num_arg(&user_buffer[i], DEC_1_DIGITS, &value);
+		max = min(DEC_1_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1779,7 +1831,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "svlan_cfi")) {
-		len = num_arg(&user_buffer[i], DEC_1_DIGITS, &value);
+		max = min(DEC_1_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
@@ -1795,7 +1848,9 @@ static ssize_t pktgen_if_write(struct file *file,
 
 	if (!strcmp(name, "tos")) {
 		__u32 tmp_value;
-		len = hex32_arg(&user_buffer[i], HEX_2_DIGITS, &tmp_value);
+
+		max = min(HEX_2_DIGITS, count - i);
+		len = hex32_arg(&user_buffer[i], max, &tmp_value);
 		if (len < 0)
 			return len;
 
@@ -1811,7 +1866,9 @@ static ssize_t pktgen_if_write(struct file *file,
 
 	if (!strcmp(name, "traffic_class")) {
 		__u32 tmp_value;
-		len = hex32_arg(&user_buffer[i], HEX_2_DIGITS, &tmp_value);
+
+		max = min(HEX_2_DIGITS, count - i);
+		len = hex32_arg(&user_buffer[i], max, &tmp_value);
 		if (len < 0)
 			return len;
 
@@ -1826,7 +1883,8 @@ static ssize_t pktgen_if_write(struct file *file,
 	}
 
 	if (!strcmp(name, "skb_priority")) {
-		len = num_arg(&user_buffer[i], DEC_9_DIGITS, &value);
+		max = min(DEC_9_DIGITS, count - i);
+		len = num_arg(&user_buffer[i], max, &value);
 		if (len < 0)
 			return len;
 
-- 
2.48.1

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