crypto: arm/chacha-neon - add missing counter increment

Commit 86cd97ec4b943af3 ("crypto: arm/chacha-neon - optimize for non-block size multiples") refactored the chacha block handling in the glue code in a way that may result in the counter increment to be omitted when calling chacha_block_xor_neon() to process a full block. This violates the API, which requires that the output IV is suitable for handling more input as long as the preceding input has been presented in round multiples of the block size.

So increment the counter after calling chacha_block_xor_neon().

---
 arch/arm/crypto/chacha-glue.c | 1 +
 1 file changed, 1 insertion(+)

index 7b5cf8430c6d..f19e6da8cdd0 100644
@@ -60,6 +60,7 @@ static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
 		chacha_block_xor_neon(state, d, s, nrounds);
 		if (d != dst)
 			memcpy(dst, buf, bytes);
+		state[12] += 1;
 	}
 }
 

2.17.1

It appears that the library API actually requires that the counter be incremented on partial blocks too. See __chacha20poly1305_encrypt().

I guess the missing increment in chacha_doneon() just wasn't noticed before because chacha20poly1305 only needs this behavior on 32-byte inputs, and chacha_doneon() is only executed when the length is over 64 bytes.

	state[12]++;