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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Dan Carpenter" <dan.carpenter@oracle.com>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
Message-ID: <lsq.1528380321.460927236@decadent.org.uk>
Subject: [PATCH 3.16 148/410] staging: lustre: libcfs: Prevent harmless
 read underflow
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3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@oracle.com>

commit 134aecbc25fd77645baaea5467b2a7ed8e9d1ea7 upstream.

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.

Fixes: d7e09d0397e8 ("staging: add Lustre file system client support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/staging/lustre/lustre/libcfs/tracefile.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/lustre/lustre/libcfs/tracefile.c
+++ b/drivers/staging/lustre/lustre/libcfs/tracefile.c
@@ -767,7 +767,7 @@ int cfs_trace_copyin_string(char *knl_bu
 		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;