From: Mateusz Nosek mateusznosek0@gmail.com
commit 921c7ebd1337d1a46783d7e15a850e12aed2eaa0 upstream.
If should_futex_fail() returns true in futex_wake_pi(), then the 'ret' variable is set to -EFAULT and then immediately overwritten. So the failure injection is non-functional.
Fix it by actually leaving the function and returning -EFAULT.
The Fixes tag is kinda blury because the initial commit which introduced failure injection was already sloppy, but the below mentioned commit broke it completely.
[ tglx: Massaged changelog ]
Fixes: 6b4f4bc9cb22 ("locking/futex: Allow low-level atomic operations to return -EAGAIN") Signed-off-by: Mateusz Nosek mateusznosek0@gmail.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Link: https://lore.kernel.org/r/20200927000858.24219-1-mateusznosek0@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/futex.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/kernel/futex.c +++ b/kernel/futex.c @@ -1605,8 +1605,10 @@ static int wake_futex_pi(u32 __user *uad */ newval = FUTEX_WAITERS | task_pid_vnr(new_owner);
- if (unlikely(should_fail_futex(true))) + if (unlikely(should_fail_futex(true))) { ret = -EFAULT; + goto out_unlock; + }
ret = cmpxchg_futex_value_locked(&curval, uaddr, uval, newval); if (!ret && (curval != uval)) {