Commit c6a771d9 authored by Will Deacon's avatar Will Deacon
Browse files

arm64: csum: Disable KASAN for do_csum() 



do_csum() over-reads the source buffer and therefore abuses
READ_ONCE_NOCHECK() to avoid tripping up KASAN. In preparation for
READ_ONCE_NOCHECK() becoming a macro, and therefore losing its
'__no_sanitize_address' annotation, just annotate do_csum() explicitly
and fall back to normal loads.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 9b4fb5ce

arch/arm64/lib/csum.c

+12 −8
Original line number Diff line number Diff line
@@ -14,7 +14,11 @@ static u64 accumulate(u64 sum, u64 data) 
	return tmp + (tmp >> 64);

}



unsigned int do_csum(const unsigned char *buff, int len)

/*

 * We over-read the buffer and this makes KASAN unhappy. Instead, disable

 * instrumentation and call kasan explicitly.

 */

unsigned int __no_sanitize_address do_csum(const unsigned char *buff, int len)

{

	unsigned int offset, shift, sum;

	const u64 *ptr;
@@ -42,7 +46,7 @@ unsigned int do_csum(const unsigned char *buff, int len) 
	 * odd/even alignment, and means we can ignore it until the very end.

	 */

	shift = offset * 8;

	data = READ_ONCE_NOCHECK(*ptr++);

	data = *ptr++;

#ifdef __LITTLE_ENDIAN

	data = (data >> shift) << shift;

#else
@@ -58,10 +62,10 @@ unsigned int do_csum(const unsigned char *buff, int len) 
	while (unlikely(len > 64)) {

		__uint128_t tmp1, tmp2, tmp3, tmp4;



		tmp1 = READ_ONCE_NOCHECK(*(__uint128_t *)ptr);

		tmp2 = READ_ONCE_NOCHECK(*(__uint128_t *)(ptr + 2));

		tmp3 = READ_ONCE_NOCHECK(*(__uint128_t *)(ptr + 4));

		tmp4 = READ_ONCE_NOCHECK(*(__uint128_t *)(ptr + 6));

		tmp1 = *(__uint128_t *)ptr;

		tmp2 = *(__uint128_t *)(ptr + 2);

		tmp3 = *(__uint128_t *)(ptr + 4);

		tmp4 = *(__uint128_t *)(ptr + 6);



		len -= 64;

		ptr += 8;
@@ -85,7 +89,7 @@ unsigned int do_csum(const unsigned char *buff, int len) 
		__uint128_t tmp;



		sum64 = accumulate(sum64, data);

		tmp = READ_ONCE_NOCHECK(*(__uint128_t *)ptr);

		tmp = *(__uint128_t *)ptr;



		len -= 16;

		ptr += 2;
@@ -100,7 +104,7 @@ unsigned int do_csum(const unsigned char *buff, int len) 
	}

	if (len > 0) {

		sum64 = accumulate(sum64, data);

		data = READ_ONCE_NOCHECK(*ptr);

		data = *ptr;

		len -= 8;

	}

	/*

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