linux-kernel - [PATCH] ipc: Limit sysctl value to IPCMNI

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Date:   Fri,  8 Jun 2018 15:49:49 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Davidlohr Bueso <dbueso@...e.de>, linux-kernel@...r.kernel.org
Subject: [PATCH] ipc: Limit sysctl value to IPCMNI

Currently shmmni proc entry accepts all entered integer values, but
the practical limit is IPCMNI (32768).  This confuses user as if a
bigger value were accepted but not applied correctly.

This patch changes the proc entry to use *_minmax variant to limit the
accepted values accordingly.

Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
 ipc/ipc_sysctl.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index 8ad93c29f511..0c8f89f54e61 100644
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -99,6 +99,7 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table, int write,
 static int zero;
 static int one = 1;
 static int int_max = INT_MAX;
+static int ipcmni = IPCMNI;
 
 static struct ctl_table ipc_kern_table[] = {
 	{
@@ -120,7 +121,9 @@ static struct ctl_table ipc_kern_table[] = {
 		.data		= &init_ipc_ns.shm_ctlmni,
 		.maxlen		= sizeof(init_ipc_ns.shm_ctlmni),
 		.mode		= 0644,
-		.proc_handler	= proc_ipc_dointvec,
+		.proc_handler	= proc_ipc_dointvec_minmax,
+		.extra1		= &zero,
+		.extra2		= &ipcmni,
 	},
 	{
 		.procname	= "shm_rmid_forced",
-- 
2.17.0