usbip: fix usbip bind writing random string after command in match_busid

commit 544c4605acc5ae4afe7dd5914147947db182f2fb upstream.

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@qindel.com>
Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/staging/usbip/userspace/src/utils.c b/drivers/staging/usbip/userspace/src/utils.c
index 2d4966e..a52189f 100644 (file)
--- a/drivers/staging/usbip/userspace/src/utils.c
+++ b/drivers/staging/usbip/userspace/src/utils.c
@@ -34,6 +34,7 @@ int modify_match_busid(char *busid, int add)
        char match_busid_attr_path[SYSFS_PATH_MAX];
        struct sysfs_attribute *match_busid_attr;
        int rc, ret = 0;
        char match_busid_attr_path[SYSFS_PATH_MAX];
        struct sysfs_attribute *match_busid_attr;
        int rc, ret = 0;

+       int cmd_size;

 
        if (strnlen(busid, SYSFS_BUS_ID_SIZE) > SYSFS_BUS_ID_SIZE - 1) {
                dbg("busid is too long");
 
        if (strnlen(busid, SYSFS_BUS_ID_SIZE) > SYSFS_BUS_ID_SIZE - 1) {
                dbg("busid is too long");


@@ -58,13 +59,15 @@ int modify_match_busid(char *busid, int add)
        }
 
        if (add)
        }
 
        if (add)

-               snprintf(buff, SYSFS_BUS_ID_SIZE + 4, "add %s", busid);
+               cmd_size = snprintf(buff, SYSFS_BUS_ID_SIZE + 4, "add %s",
+                                   busid);

        else
        else

-               snprintf(buff, SYSFS_BUS_ID_SIZE + 4, "del %s", busid);
+               cmd_size = snprintf(buff, SYSFS_BUS_ID_SIZE + 4, "del %s",
+                                   busid);

 
        dbg("write \"%s\" to %s", buff, match_busid_attr->path);
 
 
        dbg("write \"%s\" to %s", buff, match_busid_attr->path);
 

-       rc = sysfs_write_attribute(match_busid_attr, buff, sizeof(buff));
+       rc = sysfs_write_attribute(match_busid_attr, buff, cmd_size);

        if (rc < 0) {
                dbg("failed to write match_busid: %s", strerror(errno));
                ret = -1;
        if (rc < 0) {
                dbg("failed to write match_busid: %s", strerror(errno));
                ret = -1;