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    Subject[patch 53/63] futex: Validate waiter correctly in futex_proxy_trylock_atomic()
    From: Thomas Gleixner <tglx@linutronix.de>

    The loop in futex_requeue() has a sanity check for the waiter which is
    missing in futex_proxy_trylock_atomic(). In theory the key2 check is
    sufficient, but futexes are cursed so add it for completness and paranoia
    sake.

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    ---
    kernel/futex.c | 4 ++++
    1 file changed, 4 insertions(+)
    ---
    --- a/kernel/futex.c
    +++ b/kernel/futex.c
    @@ -1879,6 +1879,10 @@ futex_proxy_trylock_atomic(u32 __user *p
    if (!top_waiter)
    return 0;

    + /* Ensure that this is a waiter sitting in futex_wait_requeue_pi() */
    + if (!top_waiter->rt_waiter || top_waiter->pi_state)
    + ret = -EINVAL;
    +
    /* Ensure we requeue to the expected futex. */
    if (!match_futex(top_waiter->requeue_pi_key, key2))
    return -EINVAL;
    \
     
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      Last update: 2021-07-30 16:23    [W:2.080 / U:0.152 seconds]
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