linux-kernel - [PATCH 3/3] sysctl: report EINVAL if value is larger than UINT_MAX for proc

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Date:   Fri,  7 Apr 2017 23:51:07 +0800
From:   Liping Zhang <zlpnobody@....com>
To:     akpm@...ux-foundation.org, mingo@...nel.org, ebiederm@...ssion.com
Cc:     davem@...emloft.net, subashab@...eaurora.org,
        torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
        Liping Zhang <zlpnobody@...il.com>
Subject: [PATCH 3/3] sysctl: report EINVAL if value is larger than UINT_MAX for proc_douintvec

From: Liping Zhang <zlpnobody@...il.com>

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

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8cca4c7..e8d1ed0 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2133,6 +2133,8 @@ static int do_proc_douintvec_conv(bool *negp, unsigned long *lvalp,
 	if (write) {
 		if (*negp)
 			return -EINVAL;
+		if (*lvalp > (unsigned long) UINT_MAX)
+			return -EINVAL;
 		*valp = *lvalp;
 	} else {
 		unsigned int val = *valp;
-- 
2.5.5