Mikulas noticed in the existing do_proc_douintvec_minmax_conv() and
do_proc_dopipe_max_size_conv() introduced in this patchset, that they
inconsistently handle overflow and min/max range inputs:
For example:
0 ... param->min - 1 ---> ERANGE
param->min ... param->max ---> the value is accepted
param->max + 1 ... 0x100000000L + param->min - 1 ---> ERANGE
0x100000000L + param->min ... 0x100000000L + param->max ---> EINVAL
0x100000000L + param->max + 1, 0x200000000L + param->min - 1 ---> ERANGE
0x200000000L + param->min ... 0x200000000L + param->max ---> EINVAL
0x200000000L + param->max + 1, 0x300000000L + param->min - 1 ---> ERANGE
In do_proc_do*() routines which store values into unsigned int variables
(4 bytes wide for 64-bit builds), first validate that the input unsigned
long value (8 bytes wide for 64-bit builds) will fit inside the smaller
unsigned int variable. Then check that the unsigned int value falls
inside the specified parameter min, max range. Otherwise the unsigned
long -> unsigned int conversion drops leading bits from the input value,
leading to the inconsistent pattern Mikulas documented above.
Reported-by: Mikulas Patocka <mpato...@redhat.com>
Signed-off-by: Joe Lawrence <joe.lawre...@redhat.com>
---
kernel/sysctl.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 30b01b22014d..a04907158c90 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2587,12 +2587,13 @@ static int do_proc_douintvec_minmax_conv(unsigned long
*lvalp,
if (write) {
unsigned int val = *lvalp;
+ if (*lvalp > UINT_MAX)
+ return -EINVAL;
+
if ((param->min && *param->min > val) ||
(param->max && *param->max < val))
return -ERANGE;
- if (*lvalp > UINT_MAX)
- return -EINVAL;
*valp = val;
} else {
unsigned int val = *valp;
@@ -2643,17 +2644,18 @@ static int do_proc_dopipe_max_size_conv(unsigned long
*lvalp,
struct do_proc_dopipe_max_size_conv_param *param = data;
if (write) {
- unsigned int val = round_pipe_size(*lvalp);
+ unsigned int val;
+ if (*lvalp > UINT_MAX)
+ return -EINVAL;
+
+ val = round_pipe_size(*lvalp);
if (val == 0)
return -EINVAL;
if (param->min && *param->min > val)
return -ERANGE;
- if (*lvalp > UINT_MAX)
- return -EINVAL;
-
*valp = val;
} else {
unsigned int val = *valp;
--
1.8.3.1
