[PATCH 3.16 113/129] kernel/sysctl.c: add missing range check in do_proc_dointvec_minmax_conv

From: Ben Hutchings
Date: Sun Jul 07 2019 - 15:40:51 EST


3.16.70-rc1 review patch. If anyone has any objections, please let me know.

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

From: Zev Weiss <zev@xxxxxxxxxxxxxxxxx>

commit 8cf7630b29701d364f8df4a50e4f1f5e752b2778 upstream.

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@xxxxxxxxxxxxxxxxx
Signed-off-by: Zev Weiss <zev@xxxxxxxxxxxxxxxxx>
Cc: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
Cc: Iurii Zaikin <yzaikin@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
kernel/sysctl.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2179,7 +2179,16 @@ 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;