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

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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: Peter 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-11-22 10:57:15 +01:00 committed by Ingo Molnar
parent 0a21fc1214
commit 7c4788950b
2 changed files with 24 additions and 10 deletions
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13
arch/x86/include/asm/uaccess.h
View file

@ -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
@ -88,8 +94,11 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
* checks that the pointer is in the user space range - after calling
* this function, memory access functions may still return -EFAULT.
*/
#define access_ok(type, addr, size) \
likely(!__range_not_ok(addr, size, user_addr_max()))
#define access_ok(type, addr, size) \
({ \
WARN_ON_IN_IRQ(); \
likely(!__range_not_ok(addr, size, user_addr_max())); \
})
/*
* These are the main single-value transfer routines. They automatically

21
include/linux/preempt.h
View file

@ -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_nmi() (preempt_count() & NMI_MASK)
#define in_task() (!(preempt_count() & \
(NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))
/*
* The preempt_count offset after preempt_disable();