queue-4.4/kernel-sysctl.c-add-missing-range-check-in-do_proc_dointvec_minmax_conv.patch

   1 From 8cf7630b29701d364f8df4a50e4f1f5e752b2778 Mon Sep 17 00:00:00 2001
   2 From: Zev Weiss <zev@bewilderbeest.net>
   3 Date: Mon, 11 Mar 2019 23:28:02 -0700
   4 Subject: kernel/sysctl.c: add missing range check in do_proc_dointvec_minmax_conv
   5
   6 From: Zev Weiss <zev@bewilderbeest.net>
   7
   8 commit 8cf7630b29701d364f8df4a50e4f1f5e752b2778 upstream.
   9
  10 This bug has apparently existed since the introduction of this function
  11 in the pre-git era (4500e91754d3 in Thomas Gleixner's history.git,
  12 "[NET]: Add proc_dointvec_userhz_jiffies, use it for proper handling of
  13 neighbour sysctls.").
  14
  15 As a minimal fix we can simply duplicate the corresponding check in
  16 do_proc_dointvec_conv().
  17
  18 Link: http://lkml.kernel.org/r/20190207123426.9202-3-zev@bewilderbeest.net
  19 Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
  20 Cc: Brendan Higgins <brendanhiggins@google.com>
  21 Cc: Iurii Zaikin <yzaikin@google.com>
  22 Cc: Kees Cook <keescook@chromium.org>
  23 Cc: Luis Chamberlain <mcgrof@kernel.org>
  24 Cc: <stable@vger.kernel.org>    [2.6.2+]
  25 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  26 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  27 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  28
  29 ---
  30  kernel/sysctl.c |   11 ++++++++++-
  31  1 file changed, 10 insertions(+), 1 deletion(-)
  32
  33 --- a/kernel/sysctl.c
  34 +++ b/kernel/sysctl.c
  35 @@ -2306,7 +2306,16 @@ static int do_proc_dointvec_minmax_conv(
  36  {
  37         struct do_proc_dointvec_minmax_conv_param *param = data;
  38         if (write) {
  39 -               int val = *negp ? -*lvalp : *lvalp;
  40 +               int val;
  41 +               if (*negp) {
  42 +                       if (*lvalp > (unsigned long) INT_MAX + 1)
  43 +                               return -EINVAL;
  44 +                       val = -*lvalp;
  45 +               } else {
  46 +                       if (*lvalp > (unsigned long) INT_MAX)
  47 +                               return -EINVAL;
  48 +                       val = *lvalp;
  49 +               }
  50                 if ((param->min && *param->min > val) ||
  51                     (param->max && *param->max < val))
  52                         return -EINVAL;