linux-kernel - [PATCH 2/3] sysctl: don't print negative flag for proc

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Date:   Fri,  7 Apr 2017 23:51:06 +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 2/3] sysctl: don't print negative flag for proc_douintvec

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

I saw some very confusing sysctl output on my system:
  # cat /proc/sys/net/core/xfrm_aevent_rseqth
  -2
  # cat /proc/sys/net/core/xfrm_aevent_etime
  -10
  cat /proc/sys/net/ipv4/tcp_notsent_lowat
  -4294967295

Because we forget to set the *negp flag in proc_douintvec, so it will
become a garbage value.

Since the value related to proc_douintvec is always an unsigned integer,
so we can set *negp to false explictily to fix this issue.

Fixes: e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields")
Signed-off-by: Liping Zhang <zlpnobody@...il.com>
---
 kernel/sysctl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index acf0a5a..8cca4c7 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2136,6 +2136,7 @@ static int do_proc_douintvec_conv(bool *negp, unsigned long *lvalp,
 		*valp = *lvalp;
 	} else {
 		unsigned int val = *valp;
+		*negp = false;
 		*lvalp = (unsigned long)val;
 	}
 	return 0;
-- 
2.5.5