linux-kernel - [PATCH] usbip: fix usbip bind writing random string after command in match

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Message-ID: <1908899250.1619879.1513329680276.JavaMail.zimbra@qindel.com>
Date:   Fri, 15 Dec 2017 10:21:20 +0100 (CET)
From:   Juan Zea <juan.zea@...del.com>
To:     linux-usb@...r.kernel.org
Cc:     shuah@...nel.org, Valentina Manea <valentina.manea.m@...il.com>,
        linux-kernel@...r.kernel.org, Shuah Khan <shuahkh@....samsung.com>,
        linux-usb@...r.kernel.org
Subject: [PATCH] usbip: fix usbip bind writing random string after command
 in match_busid

usbip bind writes commands followed by random string when writing to
match_busid attribute in sysfs, caused by using full variable size
instead of string length.

Signed-off-by: Juan Zea <juan.zea@...del.com>
---
 tools/usb/usbip/src/utils.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/usb/usbip/src/utils.c b/tools/usb/usbip/src/utils.c
index 2b3d6d2..3d7b42e 100644
--- a/tools/usb/usbip/src/utils.c
+++ b/tools/usb/usbip/src/utils.c
@@ -30,6 +30,7 @@ int modify_match_busid(char *busid, int add)
 	char command[SYSFS_BUS_ID_SIZE + 4];
 	char match_busid_attr_path[SYSFS_PATH_MAX];
 	int rc;
+	int cmd_size;
 
 	snprintf(match_busid_attr_path, sizeof(match_busid_attr_path),
 		 "%s/%s/%s/%s/%s/%s", SYSFS_MNT_PATH, SYSFS_BUS_NAME,
@@ -37,12 +38,14 @@ int modify_match_busid(char *busid, int add)
 		 attr_name);
 
 	if (add)
-		snprintf(command, SYSFS_BUS_ID_SIZE + 4, "add %s", busid);
+		cmd_size = snprintf(command, SYSFS_BUS_ID_SIZE + 4, "add %s",
+				    busid);
 	else
-		snprintf(command, SYSFS_BUS_ID_SIZE + 4, "del %s", busid);
+		cmd_size = snprintf(command, SYSFS_BUS_ID_SIZE + 4, "del %s",
+				    busid);
 
 	rc = write_sysfs_attribute(match_busid_attr_path, command,
-				   sizeof(command));
+				   cmd_size);
 	if (rc < 0) {
 		dbg("failed to write match_busid: %s", strerror(errno));
 		return -1;
-- 
2.7.4