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[v2,2/4] crypto: arm64/crct10dif - revert to C code for short inputs

Message ID 20190125084915.25411-3-ard.biesheuvel@linaro.org
State Accepted
Commit d72b9d4acd548251f55b16843fc7a05dc5c80de8
Headers show
Series None | expand

Commit Message

Ard Biesheuvel Jan. 25, 2019, 8:49 a.m. UTC 
The SIMD routine ported from x86 used to have a special code path
for inputs < 16 bytes, which got lost somewhere along the way.
Instead, the current glue code aligns the input pointer to 16 bytes,
which is not really necessary on this architecture (although it
could be beneficial to performance to expose aligned data to the
the NEON routine), but this could result in inputs of less than
16 bytes to be passed in. This not only fails the new extended
tests that Eric has implemented, it also results in the code
reading past the end of the input, which could potentially result
in crashes when dealing with less than 16 bytes of input at the
end of a page which is followed by an unmapped page.

So update the glue code to only invoke the NEON routine if the
input is more than 16 bytes.

Reported-by: Eric Biggers <ebiggers@kernel.org>
Fixes: 6ef5737f3931 ("crypto: arm64/crct10dif - port x86 SSE implementation to arm64")
Cc: <stable@vger.kernel.org> # v4.10+
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---
 arch/arm64/crypto/crct10dif-ce-glue.c | 25 +++++---------------
 1 file changed, 6 insertions(+), 19 deletions(-)

-- 
2.17.1
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Patch

diff --git a/arch/arm64/crypto/crct10dif-ce-glue.c b/arch/arm64/crypto/crct10dif-ce-glue.c
index b461d62023f2..567c24f3d224 100644
--- a/arch/arm64/crypto/crct10dif-ce-glue.c
+++ b/arch/arm64/crypto/crct10dif-ce-glue.c
@@ -39,26 +39,13 @@  static int crct10dif_update(struct shash_desc *desc, const u8 *data,
 			    unsigned int length)
 {
 	u16 *crc = shash_desc_ctx(desc);
-	unsigned int l;
 
-	if (unlikely((u64)data % CRC_T10DIF_PMULL_CHUNK_SIZE)) {
-		l = min_t(u32, length, CRC_T10DIF_PMULL_CHUNK_SIZE -
-			  ((u64)data % CRC_T10DIF_PMULL_CHUNK_SIZE));
-
-		*crc = crc_t10dif_generic(*crc, data, l);
-
-		length -= l;
-		data += l;
-	}
-
-	if (length > 0) {
-		if (may_use_simd()) {
-			kernel_neon_begin();
-			*crc = crc_t10dif_pmull(*crc, data, length);
-			kernel_neon_end();
-		} else {
-			*crc = crc_t10dif_generic(*crc, data, length);
-		}
+	if (length >= CRC_T10DIF_PMULL_CHUNK_SIZE && may_use_simd()) {
+		kernel_neon_begin();
+		*crc = crc_t10dif_pmull(*crc, data, length);
+		kernel_neon_end();
+	} else {
+		*crc = crc_t10dif_generic(*crc, data, length);
 	}
 
 	return 0;