[PATCH 3.2 061/140] usbip: fix usbip bind writing random string after command in match_busid

Ben Hutchings
2018-02-28T15:23:26Z

From: Juan Zea <juan.zea@qindel.com>

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>
---
drivers/staging/usbip/userspace/src/utils.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

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

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
- 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);

- 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;