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From: Heinrich Schuchardt <xypron.glpk@gmx.de>
To: Andy Whitcroft <apw@canonical.com>, Joe Perches <joe@perches.com>
Cc: linux-kernel@vger.kernel.org, Heinrich Schuchardt <xypron.glpk@gmx.de>
Subject: [BUG] False positive in scripts/checkpatch.pl
Date: Sat, 11 Jun 2016 03:26:02 +0200
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scripts/checkpatch.pl reports

ERROR: Please use git commit description style
'commit <12+ chars of sha1> ("<title line>")'-
ie: 'commit 0123456789ab ("commit description")'

for this patch.

On 64bit systems an undetected overflow may occur in
do_proc_dointvec_minmax_conv_param as can be demonstrated
with the following example:

	# echo 9223372036854776806 > /proc/sys/kernel/threads-max
	# cat /proc/sys/kernel/threads-max
	998

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---
 kernel/sysctl.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 35f0dcb..a9e7be3 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2313,7 +2313,17 @@ static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
 {
 	struct do_proc_dointvec_minmax_conv_param *param = data;
 	if (write) {
-		int val = *negp ? -*lvalp : *lvalp;
+		int val;
+
+		if (*negp) {
+			if (*lvalp > (unsigned long) INT_MAX + 1)
+				return -EINVAL;
+			val = -*lvalp;
+		} else {
+			if (*lvalp > (unsigned long) INT_MAX)
+				return -EINVAL;
+			val = *lvalp;
+		}
 		if ((param->min && *param->min > val) ||
 		    (param->max && *param->max < val))
 			return -EINVAL;
-- 
2.1.4