[S390] dasd: fix use after free in dbf

Writing to /proc/dasd/statistics while the debug level of the
generic dasd debug entry is set to DBF_DEBUG will lead to an
use after free when accessing the debug entry later.
Since for the format string "%s" in the s390 dbf only a pointer
to the string is stored in the debug feature and the buffer used
here is freed afterwards.

To fix this just remove the debug message.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/drivers/s390/block/dasd_proc.c b/drivers/s390/block/dasd_proc.c
index 2eb0255..c4a6a31 100644 (file)
--- a/drivers/s390/block/dasd_proc.c
+++ b/drivers/s390/block/dasd_proc.c
@@ -251,7 +251,6 @@ static ssize_t dasd_stats_proc_write(struct file *file,
        buffer = dasd_get_user_string(user_buf, user_len);
        if (IS_ERR(buffer))
                return PTR_ERR(buffer);
-       DBF_EVENT(DBF_DEBUG, "/proc/dasd/statictics: '%s'\n", buffer);
 
        /* check for valid verbs */
        str = skip_spaces(buffer);