From 05fb3dbda187bbd9cc1cd0e97e5d6595af570ac6 Mon Sep 17 00:00:00 2001
From: Robin Murphy <robin.murphy@arm.com>
Date: Thu, 30 Jul 2020 10:56:49 +0100
Subject: [PATCH] arm64: csum: Fix handling of bad packets
Although iph is expected to point to at least 20 bytes of valid memory,
ihl may be bogus, for example on reception of a corrupt packet. If it
happens to be less than 5, we really don't want to run away and
dereference 16GB worth of memory until it wraps back to exactly zero...
Fixes: 0e455d8e80aa ("arm64: Implement optimised IP checksum helpers")
Reported-by: guodeqing <geffrey.guo@huawei.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/include/asm/checksum.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/checksum.h b/arch/arm64/include/asm/checksum.h
index b6f7bc6da5fb31..93a161b3bf3fee 100644
--- a/arch/arm64/include/asm/checksum.h
+++ b/arch/arm64/include/asm/checksum.h
@@ -24,16 +24,17 @@ static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
__uint128_t tmp;
u64 sum;
+ int n = ihl; /* we want it signed */
tmp = *(const __uint128_t *)iph;
iph += 16;
- ihl -= 4;
+ n -= 4;
tmp += ((tmp >> 64) | (tmp << 64));
sum = tmp >> 64;
do {
sum += *(const u32 *)iph;
iph += 4;
- } while (--ihl);
+ } while (--n > 0);
sum += ((sum >> 32) | (sum << 32));
return csum_fold((__force u32)(sum >> 32));
--
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