[PATCH 2/3] sysctl: detect overflows in proc_get_long

[Heinrich Schuchardt]

When converting strings to unsigned long overflows may occur.
These currently are not detected.

E.g. on a 32bit system
echo 0x800001234 > /proc/sys/kernel/threads-max
has the same effect as
echo 0x1234 > /proc/sys/kernel/threads-max

The patch replaces the call to deprecated simple_strtoul by a call
to kstrtoul_e.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@xxxxxx>
---
 kernel/sysctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 88ea2d6..4d9d139 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1884,7 +1884,8 @@ static int proc_get_long(char **buf, size_t *size,
 	if (!isdigit(*p))
 		return -EINVAL;
 
-	*val = simple_strtoul(p, &p, 0);
+	if (kstrtoul_e(p, &p, 0, val) < 0)
+		return -EINVAL;
 
 	len = p - tmp;
 
-- 
2.1.4

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