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Date: Tue, 3 Nov 2020 21:35:46 +0100 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Mateusz Nosek <mateusznosek0@...il.com>, Thomas Gleixner <tglx@...utronix.de>, Sasha Levin <sashal@...nel.org> Subject: [PATCH 4.19 054/191] futex: Fix incorrect should_fail_futex() handling From: Mateusz Nosek <mateusznosek0@...il.com> [ 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@...il.com> Signed-off-by: Thomas Gleixner <tglx@...utronix.de> Link: https://lore.kernel.org/r/20200927000858.24219-1-mateusznosek0@gmail.com Signed-off-by: Sasha Levin <sashal@...nel.org> --- kernel/futex.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/futex.c b/kernel/futex.c index 920d853a8e9e2..eabb9180ffa89 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1517,8 +1517,10 @@ 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)) { -- 2.27.0
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