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Revert 337f13046f
("futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op")
commit4fbf5d6837
upstream. The FUTEX_WAIT operand has historically a relative timeout which means that the clock id is irrelevant as relative timeouts on CLOCK_REALTIME are not subject to wall clock changes and therefore are mapped by the kernel to CLOCK_MONOTONIC for simplicity. If a caller would set FUTEX_CLOCK_REALTIME for FUTEX_WAIT the timeout is still treated relative vs. CLOCK_MONOTONIC and then the wait arms that timeout based on CLOCK_REALTIME which is broken and obviously has never been used or even tested. Reject any attempt to use FUTEX_CLOCK_REALTIME with FUTEX_WAIT again. The desired functionality can be achieved with FUTEX_WAIT_BITSET and a FUTEX_BITSET_MATCH_ANY argument. Fixes:337f13046f
("futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op") 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/20210422194704.834797921@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -3714,8 +3714,7 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
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if (op & FUTEX_CLOCK_REALTIME) {
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flags |= FLAGS_CLOCKRT;
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if (cmd != FUTEX_WAIT && cmd != FUTEX_WAIT_BITSET && \
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cmd != FUTEX_WAIT_REQUEUE_PI)
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if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI)
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return -ENOSYS;
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}
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