[PATCH 4.4 15/57] sysctl: report EINVAL if value is larger than UINT_MAX for proc_douintvec

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Liping Zhang <zlpnob...@gmail.com>

commit 425fffd886bae3d127a08fa6a17f2e31e24ed7ff upstream.

Currently, inputting the following command will succeed but actually the
value will be truncated:

  # echo 0x12ffffffff > /proc/sys/net/ipv4/tcp_notsent_lowat

This is not friendly to the user, so instead, we should report error
when the value is larger than UINT_MAX.

Fixes: e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields")
Signed-off-by: Liping Zhang <zlpnob...@gmail.com>
Cc: Subash Abhinov Kasiviswanathan <subas...@codeaurora.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Eric W. Biederman <ebied...@xmission.com>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 kernel/sysctl.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2067,6 +2067,8 @@ static int do_proc_douintvec_conv(bool *
        if (write) {
                if (*negp)
                        return -EINVAL;
+               if (*lvalp > UINT_MAX)
+                       return -EINVAL;
                *valp = *lvalp;
        } else {
                unsigned int val = *valp;