From b97237243a8fcd2e34ee47e87b39afd8104964b4 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Fri, 17 Jan 2020 15:48:39 +0000 Subject: [PATCH] arm64: csum: Fix pathological zero-length calls In validating the checksumming results of the new routine, I sadly neglected to test its not-checksumming results. Thus it slipped through that the one case where @buff is already dword-aligned and @len = 0 manages to defeat the tail-masking logic and behave as if @len = 8. For a zero length it doesn't make much sense to deference @buff anyway, so just add an early return (which has essentially zero impact on performance). Signed-off-by: Robin Murphy Signed-off-by: Will Deacon --- arch/arm64/lib/csum.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/lib/csum.c b/arch/arm64/lib/csum.c index 847eb725ce09..1f82c66b32ea 100644 --- a/arch/arm64/lib/csum.c +++ b/arch/arm64/lib/csum.c @@ -20,6 +20,9 @@ unsigned int do_csum(const unsigned char *buff, int len) const u64 *ptr; u64 data, sum64 = 0; + if (unlikely(len == 0)) + return 0; + offset = (unsigned long)buff & 7; /* * This is to all intents and purposes safe, since rounding down cannot