[patch 02/38] kernel/sysctl.c: add missing range check in do_proc_dointvec_minmax_conv

[patch 02/38] kernel/sysctl.c: add missing range check in do_proc_dointvec_minmax_conv

[akpm]

From: Zev Weiss <zev@bewilderbeest.net>
Subject: kernel/sysctl.c: add missing range check in do_proc_dointvec_minmax_conv

This bug has apparently existed since the introduction of this function in
the pre-git era (4500e91754d3 in Thomas Gleixner's history.git, "[NET]:
Add proc_dointvec_userhz_jiffies, use it for proper handling of neighbour
sysctls.").  As a minimal fix we can simply duplicate the corresponding
check in do_proc_dointvec_conv().

Link: http://lkml.kernel.org/r/20190207123426.9202-3-zev@bewilderbeest.net
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: <stable@vger.kernel.org>	[2.6.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---


--- a/kernel/sysctl.c~kernel-sysctlc-add-missing-range-check-in-do_proc_dointvec_minmax_conv
+++ a/kernel/sysctl.c
@@ -2645,7 +2645,16 @@ static int do_proc_dointvec_minmax_conv(
 {
 	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;
_