[patch V4 62/68] futex: Reorder sanity checks in futex_requeue()

Thomas Gleixner
2021-08-11T12:26:09Z

No point in allocating memory when the input parameters are bogus. Validate
all parameters before proceeding.

Suggested-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V4: New patch
---
kernel/futex.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1934,13 +1934,6 @@ static int futex_requeue(u32 __user *uad
return -EINVAL;

/*
- * requeue_pi requires a pi_state, try to allocate it now
- * without any locks in case it fails.
- */
- if (refill_pi_state_cache())
- return -ENOMEM;
-
- /*
* futex_requeue() allows the caller to define the number
* of waiters to wake up via the @nr_wake argument. With
* REQUEUE_PI waking up more than one waiter is creating
@@ -1963,6 +1956,13 @@ static int futex_requeue(u32 __user *uad
*/
if (nr_wake != 1)
return -EINVAL;
+
+ /*
+ * requeue_pi requires a pi_state, try to allocate it now
+ * without any locks in case it fails.
+ */
+ if (refill_pi_state_cache())
+ return -ENOMEM;
}