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Subject[PATCH 5.0 049/238] crypto: arm64/aes-ccm - fix logical bug in AAD MAC handling
Date
5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

commit eaf46edf6ea89675bd36245369c8de5063a0272c upstream.

The NEON MAC calculation routine fails to handle the case correctly
where there is some data in the buffer, and the input fills it up
exactly. In this case, we enter the loop at the end with w8 == 0,
while a negative value is assumed, and so the loop carries on until
the increment of the 32-bit counter wraps around, which is quite
obviously wrong.

So omit the loop altogether in this case, and exit right away.

Reported-by: Eric Biggers <ebiggers@kernel.org>
Fixes: a3fd82105b9d1 ("arm64/crypto: AES in CCM mode using ARMv8 Crypto ...")
Cc: stable@vger.kernel.org
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/arm64/crypto/aes-ce-ccm-core.S | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/arch/arm64/crypto/aes-ce-ccm-core.S
+++ b/arch/arm64/crypto/aes-ce-ccm-core.S
@@ -74,12 +74,13 @@ ENTRY(ce_aes_ccm_auth_data)
beq 10f
ext v0.16b, v0.16b, v0.16b, #1 /* rotate out the mac bytes */
b 7b
-8: mov w7, w8
+8: cbz w8, 91f
+ mov w7, w8
add w8, w8, #16
9: ext v1.16b, v1.16b, v1.16b, #1
adds w7, w7, #1
bne 9b
- eor v0.16b, v0.16b, v1.16b
+91: eor v0.16b, v0.16b, v1.16b
st1 {v0.16b}, [x0]
10: str w8, [x3]
ret

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