The following commit has been merged into the locking/urgent branch of tip:
Commit-ID: 921c7ebd1337d1a46783d7e15a850e12aed2eaa0
Gitweb: https://git.kernel.org/tip/921c7ebd1337d1a46783d7e15a850e12aed2eaa0
Author: Mateusz Nosek <mateusznosek0@xxxxxxxxx>
AuthorDate: Sun, 27 Sep 2020 02:08:58 +02:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Wed, 28 Oct 2020 15:48:51 +01:00
futex: Fix incorrect should_fail_futex() handling
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@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200927000858.24219-1-mateusznosek0@xxxxxxxxx
---
kernel/futex.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index a587669..39681bf 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1502,8 +1502,10 @@ 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)) {
|