futex: Do not apply time namespace adjustment on FUTEX_LOCK_PI

BugLink: https://bugs.launchpad.net/bugs/1928857
commit cdf78db4070967869e4d027c11f4dd825d8f815a upstream.

FUTEX_LOCK_PI does not require to have the FUTEX_CLOCK_REALTIME bit set
because it has been using CLOCK_REALTIME based absolute timeouts
forever. Due to that, the time namespace adjustment which is applied when
FUTEX_CLOCK_REALTIME is not set, will wrongly take place for FUTEX_LOCK_PI
and wreckage the timeout.

Exclude it from that procedure.

Fixes: c2f7d08cccf4 ("futex: Adjust absolute futex timeouts with per time namespace offset")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210422194704.984540159@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/kernel/futex.c b/kernel/futex.c
index 8dc4d64aae6d80ee877e3061da0593340ce47604..57662f970c06ee36813c98958bd2aa9e48e8efe2 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3782,7 +3782,7 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
                t = timespec64_to_ktime(ts);
                if (cmd == FUTEX_WAIT)
                        t = ktime_add_safe(ktime_get(), t);
-               else if (!(op & FUTEX_CLOCK_REALTIME))
+               else if (cmd != FUTEX_LOCK_PI && !(op & FUTEX_CLOCK_REALTIME))
                        t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
                tp = &t;
        }
@@ -3976,7 +3976,7 @@ SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
                t = timespec64_to_ktime(ts);
                if (cmd == FUTEX_WAIT)
                        t = ktime_add_safe(ktime_get(), t);
-               else if (!(op & FUTEX_CLOCK_REALTIME))
+               else if (cmd != FUTEX_LOCK_PI && !(op & FUTEX_CLOCK_REALTIME))
                        t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
                tp = &t;
        }