The following commit has been merged into the locking/kcsan branch of tip: Commit-ID: 5a7d7f5d57f61d650619b89c1b7d4adcf4fdecfe Gitweb: https://git.kernel.org/tip/5a7d7f5d57f61d650619b89c1b7d4adcf4fdecfe Author: Will Deacon <will@xxxxxxxxxx> AuthorDate: Mon, 11 May 2020 21:41:41 +01:00 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitterDate: Tue, 12 May 2020 11:04:13 +02:00 arm64: csum: Disable KASAN for do_csum() do_csum() over-reads the source buffer and therefore abuses READ_ONCE_NOCHECK() on a 128-bit type to avoid tripping up KASAN. In preparation for READ_ONCE_NOCHECK() requiring an atomic access, and therefore failing to build when fed a '__uint128_t', annotate do_csum() explicitly with '__no_sanitize_address' and fall back to normal loads. Signed-off-by: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Acked-by: Robin Murphy <robin.murphy@xxxxxxx> Acked-by: Mark Rutland <mark.rutland@xxxxxxx> Link: https://lkml.kernel.org/r/20200511204150.27858-10-will@xxxxxxxxxx --- arch/arm64/lib/csum.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/arch/arm64/lib/csum.c b/arch/arm64/lib/csum.c index 60eccae..78b87a6 100644 --- a/arch/arm64/lib/csum.c +++ b/arch/arm64/lib/csum.c @@ -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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