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authorThomas Gleixner <tglx@linutronix.de>2010-02-02 11:40:27 +0100
committerThomas Gleixner <tglx@linutronix.de>2010-02-03 15:13:22 +0100
commit51246bfd189064079c54421507236fd2723b18f3 (patch)
tree060060ee3fe1cfe7c3ab510e4aff8a9dc3a7c64f /kernel/cpu.c
parent5ecb01cfdf96c5f465192bdb2a4fd4a61a24c6cc (diff)
futex: Handle user space corruption gracefully
If the owner of a PI futex dies we fix up the pi_state and set pi_state->owner to NULL. When a malicious or just sloppy programmed user space application sets the futex value to 0 e.g. by calling pthread_mutex_init(), then the futex can be acquired again. A new waiter manages to enqueue itself on the pi_state w/o damage, but on unlock the kernel dereferences pi_state->owner and oopses. Prevent this by checking pi_state->owner in the unlock path. If pi_state->owner is not current we know that user space manipulated the futex value. Ignore the mess and return -EINVAL. This catches the above case and also the case where a task hijacks the futex by setting the tid value and then tries to unlock it. Reported-by: Jermome Marchand <jmarchan@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Darren Hart <dvhltc@us.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: <stable@kernel.org>
Diffstat (limited to 'kernel/cpu.c')
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