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arm64: csum: Disable KASAN for do_csum()

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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: Will Deacon <will@kernel.org>
This commit is contained in:
Will Deacon 2020-04-14 22:22:47 +01:00
parent 9b4fb5cec0
commit c6a771d932
1 changed files with 12 additions and 8 deletions
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20
arch/arm64/lib/csum.c
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@ -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;
}
/*