On Wed, 23 Jan 2019 at 23:52, Eric Biggers ebiggers@kernel.org wrote:

From: Eric Biggers ebiggers@google.com

The arm64 NEON bit-sliced implementation of AES-CTR fails the improved skcipher tests because it sometimes produces the wrong ciphertext. The bug is that the final keystream block isn't returned from the assembly code when the number of non-final blocks is zero. This can happen if the input data ends a few bytes after a page boundary. In this case the last bytes get "encrypted" by XOR'ing them with uninitialized memory.

Fix the assembly code to return the final keystream block when needed.

Fixes: 88a3f582bea9 ("crypto: arm64/aes - don't use IV buffer to return final keystream block") Cc: stable@vger.kernel.org # v4.11+ Cc: Ard Biesheuvel ard.biesheuvel@linaro.org Signed-off-by: Eric Biggers ebiggers@google.com

Reviewed-by: Ard Biesheuvel ard.biesheuvel@linaro.org

---

arch/arm64/crypto/aes-neonbs-core.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/crypto/aes-neonbs-core.S b/arch/arm64/crypto/aes-neonbs-core.S index e613a87f8b53..8432c8d0dea6 100644 --- a/arch/arm64/crypto/aes-neonbs-core.S +++ b/arch/arm64/crypto/aes-neonbs-core.S @@ -971,18 +971,22 @@ CPU_LE( rev x8, x8 )

8: next_ctr v0 st1 {v0.16b}, [x24]

•   cbz             x23, 0f
  

•   cbz             x23, .Lctr_done
  
    cond_yield_neon 98b
    b               99b
  
  

-0: frame_pop +.Lctr_done:

•   frame_pop
    ret
  
    /*
     * If we are handling the tail of the input (x6 != NULL), return the
     * final keystream block back to the caller.
     */
  

+0: cbz x25, 8b

•   st1             {v0.16b}, [x25]
  

•   b               8b
  

1: cbz x25, 8b st1 {v1.16b}, [x25] b 8b -- 2.20.1.321.g9e740568ce-goog