[PATCH 2/2] kernel/sysctl.c: define minmax conv functions in terms of non-minmax versions

[Zev Weiss]

do_proc_do[u]intvec_minmax_conv() had included open-coded versions of
do_proc_do[u]intvec_conv(), though the signed one omitted the check
that the value is in [INT_MIN, INT_MAX].  Rather than increase the
duplication further by copying the additional check, we can instead
refactor both to be defined in terms of their non-bounded counterparts
(plus the added check).

Signed-off-by: Zev Weiss <z...@bewilderbeest.net>
---
 kernel/sysctl.c | 50 ++++++++++++++++++++++++++-----------------------
 1 file changed, 27 insertions(+), 23 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 5fc724e4e454..4a0261d32401 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2562,23 +2562,26 @@ static int do_proc_dointvec_minmax_conv(bool *negp, 
unsigned long *lvalp,
                                        int *valp,
                                        int write, void *data)
 {
+       int tmp, ret;
        struct do_proc_dointvec_minmax_conv_param *param = data;
+
+       /*
+        * First write to a temporary local int so we can bounds-check it
+        * before touching *valp.
+        */
+       int *ip = write ? &tmp : valp;
+
+       ret = do_proc_dointvec_conv(negp, lvalp, ip, write, data);
+       if (ret)
+               return ret;
+
        if (write) {
-               int val = *negp ? -*lvalp : *lvalp;
-               if ((param->min && *param->min > val) ||
-                   (param->max && *param->max < val))
+               if ((param->min && *param->min > tmp) ||
+                   (param->max && *param->max < tmp))
                        return -EINVAL;
-               *valp = val;
-       } else {
-               int val = *valp;
-               if (val < 0) {
-                       *negp = true;
-                       *lvalp = -(unsigned long)val;
-               } else {
-                       *negp = false;
-                       *lvalp = (unsigned long)val;
-               }
+               *valp = tmp;
        }
+
        return 0;
 }
 
@@ -2627,22 +2630,23 @@ static int do_proc_douintvec_minmax_conv(unsigned long 
*lvalp,
                                         unsigned int *valp,
                                         int write, void *data)
 {
+       int ret;
+       unsigned int tmp;
        struct do_proc_douintvec_minmax_conv_param *param = data;
 
-       if (write) {
-               unsigned int val = *lvalp;
+       /* write via temporary local uint for bounds-checking */
+       unsigned int *up = write ? &tmp : valp;
 
-               if (*lvalp > UINT_MAX)
-                       return -EINVAL;
+       ret = do_proc_douintvec_conv(lvalp, up, write, data);
+       if (ret)
+               return ret;
 
-               if ((param->min && *param->min > val) ||
-                   (param->max && *param->max < val))
+       if (write) {
+               if ((param->min && *param->min > tmp) ||
+                   (param->max && *param->max < tmp))
                        return -ERANGE;
 
-               *valp = val;
-       } else {
-               unsigned int val = *valp;
-               *lvalp = (unsigned long) val;
+               *valp = tmp;
        }
 
        return 0;
-- 
2.20.1