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36903abedf
The __range_not_ok() helper is an x86 (and sparc64) specific interface that does roughly the same thing as __access_ok(), but with different calling conventions. Change this to use the normal interface in order for consistency as we clean up all access_ok() implementations. This changes the limit from TASK_SIZE to TASK_SIZE_MAX, which Al points out is the right thing do do here anyway. The callers have to use __access_ok() instead of the normal access_ok() though, because on x86 that contains a WARN_ON_IN_IRQ() check that cannot be used inside of NMI context while tracing. The check in copy_code() is not needed any more, because this one is already done by copy_from_user_nmi(). Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Suggested-by: Christoph Hellwig <hch@infradead.org> Link: https://lore.kernel.org/lkml/YgsUKcXGR7r4nINj@zeniv-ca.linux.org.uk/ Signed-off-by: Arnd Bergmann <arnd@arndb.de>
52 lines
1.4 KiB
C
52 lines
1.4 KiB
C
/*
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* User address space access functions.
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*
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* For licencing details see kernel-base/COPYING
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*/
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#include <linux/uaccess.h>
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#include <linux/export.h>
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#include <asm/tlbflush.h>
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/**
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* copy_from_user_nmi - NMI safe copy from user
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* @to: Pointer to the destination buffer
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* @from: Pointer to a user space address of the current task
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* @n: Number of bytes to copy
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*
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* Returns: The number of not copied bytes. 0 is success, i.e. all bytes copied
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*
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* Contrary to other copy_from_user() variants this function can be called
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* from NMI context. Despite the name it is not restricted to be called
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* from NMI context. It is safe to be called from any other context as
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* well. It disables pagefaults across the copy which means a fault will
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* abort the copy.
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*
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* For NMI context invocations this relies on the nested NMI work to allow
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* atomic faults from the NMI path; the nested NMI paths are careful to
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* preserve CR2.
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*/
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unsigned long
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copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
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{
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unsigned long ret;
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if (!__access_ok(from, n))
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return n;
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if (!nmi_uaccess_okay())
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return n;
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/*
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* Even though this function is typically called from NMI/IRQ context
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* disable pagefaults so that its behaviour is consistent even when
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* called from other contexts.
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*/
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pagefault_disable();
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ret = __copy_from_user_inatomic(to, from, n);
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pagefault_enable();
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return ret;
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}
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EXPORT_SYMBOL_GPL(copy_from_user_nmi);
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