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Commit 7c478895 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

x86/uaccess, sched/preempt: Verify access_ok() context 



I recently encountered wreckage because access_ok() was used where it
should not be, add an explicit WARN when access_ok() is used wrongly.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 0a21fc12

arch/x86/include/asm/uaccess.h

+11 −2
Original line number Diff line number Diff line
@@ -68,6 +68,12 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un 
	__chk_range_not_ok((unsigned long __force)(addr), size, limit); \

})



#ifdef CONFIG_DEBUG_ATOMIC_SLEEP

# define WARN_ON_IN_IRQ()	WARN_ON_ONCE(!in_task())

#else

# define WARN_ON_IN_IRQ()

#endif



/**

 * access_ok: - Checks if a user space pointer is valid

 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
@@ -89,7 +95,10 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un 
 * this function, memory access functions may still return -EFAULT.

 */

#define access_ok(type, addr, size)					\

	likely(!__range_not_ok(addr, size, user_addr_max()))

({									\

	WARN_ON_IN_IRQ();						\

	likely(!__range_not_ok(addr, size, user_addr_max()));		\

})



/*

 * These are the main single-value transfer routines.  They automatically

include/linux/preempt.h

+13 −8
Original line number Diff line number Diff line
@@ -65,19 +65,24 @@ 


/*

 * Are we doing bottom half or hardware interrupt processing?

 * Are we in a softirq context? Interrupt context?

 * in_softirq - Are we currently processing softirq or have bh disabled?

 * in_serving_softirq - Are we currently processing softirq?

 *

 * in_irq()       - We're in (hard) IRQ context

 * in_softirq()   - We have BH disabled, or are processing softirqs

 * in_interrupt() - We're in NMI,IRQ,SoftIRQ context or have BH disabled

 * in_serving_softirq() - We're in softirq context

 * in_nmi()       - We're in NMI context

 * in_task()	  - We're in task context

 *

 * Note: due to the BH disabled confusion: in_softirq(),in_interrupt() really

 *       should not be used in new code.

 */

#define in_irq()		(hardirq_count())

#define in_softirq()		(softirq_count())

#define in_interrupt()		(irq_count())

#define in_serving_softirq()	(softirq_count() & SOFTIRQ_OFFSET)



/*

 * Are we in NMI context?

 */

#define in_nmi()		(preempt_count() & NMI_MASK)

#define in_task()		(!(preempt_count() & \

				   (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))



/*

 * The preempt_count offset after preempt_disable();