From: Mateusz Nosek mateusznosek0@gmail.com
stable inclusion from linux-4.19.155 commit ae5aa5685c7cc1def1e07e0ab562087c5b8c78e7
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[ Upstream commit 921c7ebd1337d1a46783d7e15a850e12aed2eaa0 ]
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: Yang Yingliang yangyingliang@huawei.com --- kernel/futex.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/futex.c b/kernel/futex.c index 28b321e23053..04bc59324d7f 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1522,8 +1522,10 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_ */ 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)) {