40 lines
1.4 KiB
Diff
40 lines
1.4 KiB
Diff
From dc516e6e8dfdaecf01efc7ee643a234191761062 Mon Sep 17 00:00:00 2001
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From: Tim Gover <tim.gover@raspberrypi.org>
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Date: Thu, 14 Mar 2019 10:16:02 +0000
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Subject: [PATCH] Fix copy_from_user if BCM2835_FAST_MEMCPY=n
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The change which introduced CONFIG_BCM2835_FAST_MEMCPY unconditionally
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changed the behaviour of arm_copy_from_user. The page pinning code
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is not safe on ARMv7 if LPAE & high memory is enabled and causes
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crashes which look like PTE corruption.
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Make __copy_from_user_memcpy conditional on CONFIG_2835_FAST_MEMCPY=y
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which is really an ARMv6 / Pi1 optimization and not necessary on newer
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ARM processors.
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---
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arch/arm/lib/uaccess_with_memcpy.c | 6 ++++++
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1 file changed, 6 insertions(+)
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--- a/arch/arm/lib/uaccess_with_memcpy.c
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+++ b/arch/arm/lib/uaccess_with_memcpy.c
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@@ -254,6 +254,7 @@ arm_copy_to_user(void __user *to, const
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unsigned long __must_check
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arm_copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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+#ifdef CONFIG_BCM2835_FAST_MEMCPY
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/*
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* This test is stubbed out of the main function above to keep
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* the overhead for small copies low by avoiding a large
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@@ -268,6 +269,11 @@ arm_copy_from_user(void *to, const void
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} else {
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n = __copy_from_user_memcpy(to, from, n);
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}
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+#else
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+ unsigned long ua_flags = uaccess_save_and_enable();
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+ n = __copy_from_user_std(to, from, n);
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+ uaccess_restore(ua_flags);
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+#endif
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return n;
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}
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