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crypto: arm64/aes-ccm - fix logical bug in AAD MAC handling 

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 ...")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Ard Biesheuvel 2019-01-24 17:33:45 +01:00 committed by syphyr
parent 0d953282c3
commit 32be75b125
1 changed files with 3 additions and 2 deletions
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5
arch/arm64/crypto/aes-ce-ccm-core.S
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@ -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