LU-9859 libcfs: Prevent harmless read underflow

Because this is a post-op instead of a pre-op, then it means we check
if knl_buffer[-1] is a space.  It doesn't really hurt anything, but
it causes a static checker warning so let's fix it.

Linux-commit: 134aecbc25fd77645baaea5467b2a7ed8e9d1ea7

Change-Id: I40fee264eb1ac461baa183f199b4e5e1b5eb26f5
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/36567
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Shaun Tancheff <stancheff@cray.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/libcfs/libcfs/tracefile.c b/libcfs/libcfs/tracefile.c
index 926451f..81cb393 100644 (file)
--- a/libcfs/libcfs/tracefile.c
+++ b/libcfs/libcfs/tracefile.c
@@ -722,7 +722,7 @@ int cfs_trace_copyin_string(char *knl_buffer, int knl_buffer_nob,
                 return -EFAULT;
 
         nob = strnlen(knl_buffer, usr_buffer_nob);
-        while (nob-- >= 0)                      /* strip trailing whitespace */
+       while (--nob >= 0)                      /* strip trailing whitespace */
                 if (!isspace(knl_buffer[nob]))
                         break;