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