linux-kernel - [PATCH v4 2/6] proc/sysctl: Check for invalid flags bits

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Date:   Mon, 12 Mar 2018 16:15:40 -0400
From:   Waiman Long <longman@...hat.com>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Matthew Wilcox <willy@...radead.org>,
        Waiman Long <longman@...hat.com>
Subject: [PATCH v4 2/6] proc/sysctl: Check for invalid flags bits

Checking code is added to check for invalid flags in the ctl_table
and return error if an unknown flag is used.

Signed-off-by: Waiman Long <longman@...hat.com>
---
 fs/proc/proc_sysctl.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 493c975..67c0c82 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -1092,6 +1092,16 @@ static int sysctl_check_table_array(const char *path, struct ctl_table *table)
 	return err;
 }
 
+static int sysctl_check_flags(const char *path, struct ctl_table *table)
+{
+	int err = 0;
+
+	if (table->flags & ~CTL_TABLE_FLAGS_ALL)
+		err = sysctl_err(path, table, "invalid flags");
+
+	return err;
+}
+
 static int sysctl_check_table(const char *path, struct ctl_table *table)
 {
 	int err = 0;
@@ -1111,6 +1121,8 @@ static int sysctl_check_table(const char *path, struct ctl_table *table)
 		    (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
 			if (!table->data)
 				err |= sysctl_err(path, table, "No data");
+			if (table->flags)
+				err |= sysctl_check_flags(path, table);
 			if (!table->maxlen)
 				err |= sysctl_err(path, table, "No maxlen");
 			else
-- 
1.8.3.1