[PATCH] kernel/sys.c: fix prototype of prctl_get_tid_address()

From: Rasmus Villemoes
Date: Fri Oct 23 2020 - 21:12:35 EST


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@xxxxxxxxx>
Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
---
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