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From:   Rasmus Villemoes <linux@rasmusvillemoes.dk>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Yi Wang <wang.yi59@zte.com.cn>,
        Liao Pingfang <liao.pingfang@zte.com.cn>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        kernel test robot <lkp@intel.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH] kernel/sys.c: fix prototype of prctl_get_tid_address()
Date:   Sat, 24 Oct 2020 03:04:26 +0200
Message-Id: <20201024010427.27405-1-linux@rasmusvillemoes.dk>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

tid_addr is not a "pointer to (pointer to int in userspace)"; it is in
fact a "pointer to (pointer to int in userspace) in userspace". So
sparse rightfully complains about passing a kernel pointer to
put_user().

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 kernel/sys.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index 6401880dff74a80a4594..85395f5cebc34d073cf4 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2238,12 +2238,12 @@ static int prctl_set_mm(int opt, unsigned long addr,
 }
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
-static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
+static int prctl_get_tid_address(struct task_struct *me, int __user * __user *tid_addr)
 {
 	return put_user(me->clear_child_tid, tid_addr);
 }
 #else
-static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
+static int prctl_get_tid_address(struct task_struct *me, int __user * __user *tid_addr)
 {
 	return -EINVAL;
 }
@@ -2427,7 +2427,7 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 		error = prctl_set_mm(arg2, arg3, arg4, arg5);
 		break;
 	case PR_GET_TID_ADDRESS:
-		error = prctl_get_tid_address(me, (int __user **)arg2);
+		error = prctl_get_tid_address(me, (int __user * __user *)arg2);
 		break;
 	case PR_SET_CHILD_SUBREAPER:
 		me->signal->is_child_subreaper = !!arg2;
-- 
2.23.0