[PATCH -next V2] sysctl: returns -EINVAL when a negative value is passed to proc_doulongvec_minmax

[Baokun Li]

When we pass a negative value to the proc_doulongvec_minmax() function,
the function returns 0, but the corresponding interface value does not
change.

we can easily reproduce this problem with the following commands:
    `cd /proc/sys/fs/epoll`
    `echo -1 > max_user_watches; echo $?; cat max_user_watches`

This function requires a non-negative number to be passed in, so when
a negative number is passed in, -EINVAL is returned.

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
---
V1->V2:
	Modify the judgment position.

 kernel/sysctl.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 7f07b058b180..4211e39a5fd3 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1147,10 +1147,11 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table,
 			err = proc_get_long(&p, &left, &val, &neg,
 					     proc_wspace_sep,
 					     sizeof(proc_wspace_sep), NULL);
-			if (err)
+			if (err || neg) {
+				err = -EINVAL;
 				break;
-			if (neg)
-				continue;
+			}
+
 			val = convmul * val / convdiv;
 			if ((min && val < *min) || (max && val > *max)) {
 				err = -EINVAL;
-- 
2.31.1