[PATCH] arm64: fix the illegal address access in some cases

[guodeqing]

The ihl value of ip header is smaller than 5 in some cases, if the
ihl value is smaller than 5, then the next code will access the illegal
address, and the system will panic.

Here I add the check of the ihl value to solve this problem.

Fixes: 0e455d8e80aa (arm64: Implement optimised IP checksum helpers)
Signed-off-by: guodeqing <geffrey.guo at huawei.com>
---
 arch/arm64/include/asm/checksum.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/include/asm/checksum.h b/arch/arm64/include/asm/checksum.h
index b6f7bc6da5fb..5a7d9acfb6ea 100644
--- a/arch/arm64/include/asm/checksum.h
+++ b/arch/arm64/include/asm/checksum.h
@@ -25,6 +25,9 @@ static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
 	__uint128_t tmp;
 	u64 sum;
 
+	if (unlikely(ihl < 5))
+		return 1;
+
 	tmp = *(const __uint128_t *)iph;
 	iph += 16;
 	ihl -= 4;
-- 
2.17.1