linux-kernel - [PATCH 4.4 15/57] sysctl: report EINVAL if value is larger than UINT_MAX for proc

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Date:   Thu, 13 Jul 2017 17:42:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Liping Zhang <zlpnobody@...il.com>,
        Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.4 15/57] sysctl: report EINVAL if value is larger than UINT_MAX for proc_douintvec

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

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

From: Liping Zhang <zlpnobody@...il.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 <zlpnobody@...il.com>
Cc: Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Eric W. Biederman <ebiederm@...ssion.com>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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;