linux-kernel - [PATCH] pcmcia: Use scnprintf() for avoiding potential buffer overflow

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Date:   Wed, 11 Mar 2020 10:04:26 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Dominik Brodowski <linux@...inikbrodowski.net>
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] pcmcia: Use scnprintf() for avoiding potential buffer overflow

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
 drivers/pcmcia/rsrc_nonstatic.c |  6 +++---
 drivers/pcmcia/yenta_socket.c   | 10 +++++-----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/pcmcia/rsrc_nonstatic.c b/drivers/pcmcia/rsrc_nonstatic.c
index 9e6922c08ef6..3b05760e69d6 100644
--- a/drivers/pcmcia/rsrc_nonstatic.c
+++ b/drivers/pcmcia/rsrc_nonstatic.c
@@ -1076,7 +1076,7 @@ static ssize_t show_io_db(struct device *dev,
 	for (p = data->io_db.next; p != &data->io_db; p = p->next) {
 		if (ret > (PAGE_SIZE - 10))
 			continue;
-		ret += snprintf(&buf[ret], (PAGE_SIZE - ret - 1),
+		ret += scnprintf(&buf[ret], (PAGE_SIZE - ret - 1),
 				"0x%08lx - 0x%08lx\n",
 				((unsigned long) p->base),
 				((unsigned long) p->base + p->num - 1));
@@ -1133,7 +1133,7 @@ static ssize_t show_mem_db(struct device *dev,
 	     p = p->next) {
 		if (ret > (PAGE_SIZE - 10))
 			continue;
-		ret += snprintf(&buf[ret], (PAGE_SIZE - ret - 1),
+		ret += scnprintf(&buf[ret], (PAGE_SIZE - ret - 1),
 				"0x%08lx - 0x%08lx\n",
 				((unsigned long) p->base),
 				((unsigned long) p->base + p->num - 1));
@@ -1142,7 +1142,7 @@ static ssize_t show_mem_db(struct device *dev,
 	for (p = data->mem_db.next; p != &data->mem_db; p = p->next) {
 		if (ret > (PAGE_SIZE - 10))
 			continue;
-		ret += snprintf(&buf[ret], (PAGE_SIZE - ret - 1),
+		ret += scnprintf(&buf[ret], (PAGE_SIZE - ret - 1),
 				"0x%08lx - 0x%08lx\n",
 				((unsigned long) p->base),
 				((unsigned long) p->base + p->num - 1));
diff --git a/drivers/pcmcia/yenta_socket.c b/drivers/pcmcia/yenta_socket.c
index 49b1c6a1bdbe..bf6529b0b5b0 100644
--- a/drivers/pcmcia/yenta_socket.c
+++ b/drivers/pcmcia/yenta_socket.c
@@ -180,12 +180,12 @@ static ssize_t show_yenta_registers(struct device *yentadev, struct device_attri
 	for (i = 0; i < 0x24; i += 4) {
 		unsigned val;
 		if (!(i & 15))
-			offset += snprintf(buf + offset, PAGE_SIZE - offset, "\n%02x:", i);
+			offset += scnprintf(buf + offset, PAGE_SIZE - offset, "\n%02x:", i);
 		val = cb_readl(socket, i);
-		offset += snprintf(buf + offset, PAGE_SIZE - offset, " %08x", val);
+		offset += scnprintf(buf + offset, PAGE_SIZE - offset, " %08x", val);
 	}
 
-	offset += snprintf(buf + offset, PAGE_SIZE - offset, "\n\nExCA registers:");
+	offset += scnprintf(buf + offset, PAGE_SIZE - offset, "\n\nExCA registers:");
 	for (i = 0; i < 0x45; i++) {
 		unsigned char val;
 		if (!(i & 7)) {
@@ -193,10 +193,10 @@ static ssize_t show_yenta_registers(struct device *yentadev, struct device_attri
 				memcpy(buf + offset, " -", 2);
 				offset += 2;
 			} else
-				offset += snprintf(buf + offset, PAGE_SIZE - offset, "\n%02x:", i);
+				offset += scnprintf(buf + offset, PAGE_SIZE - offset, "\n%02x:", i);
 		}
 		val = exca_readb(socket, i);
-		offset += snprintf(buf + offset, PAGE_SIZE - offset, " %02x", val);
+		offset += scnprintf(buf + offset, PAGE_SIZE - offset, " %02x", val);
 	}
 	buf[offset++] = '\n';
 	return offset;
-- 
2.16.4