29 lines
989 B
Diff
29 lines
989 B
Diff
From: Robin Murphy <robin.murphy@arm.com>
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Date: Fri, 17 Jan 2020 15:48:39 +0000
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Subject: [PATCH] arm64: csum: Fix pathological zero-length calls
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In validating the checksumming results of the new routine, I sadly
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neglected to test its not-checksumming results. Thus it slipped through
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that the one case where @buff is already dword-aligned and @len = 0
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manages to defeat the tail-masking logic and behave as if @len = 8.
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For a zero length it doesn't make much sense to deference @buff anyway,
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so just add an early return (which has essentially zero impact on
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performance).
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Signed-off-by: Robin Murphy <robin.murphy@arm.com>
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Signed-off-by: Will Deacon <will@kernel.org>
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---
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--- a/arch/arm64/lib/csum.c
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+++ b/arch/arm64/lib/csum.c
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@@ -20,6 +20,9 @@ unsigned int do_csum(const unsigned char
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const u64 *ptr;
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u64 data, sum64 = 0;
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+ if (unlikely(len == 0))
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+ return 0;
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+
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offset = (unsigned long)buff & 7;
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/*
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* This is to all intents and purposes safe, since rounding down cannot
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