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crypto: lrw - Fix out-of bounds access on counter overflow

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When the LRW block counter overflows, the current implementation returns
128 as the index to the precomputed multiplication table, which has 128
entries. This patch fixes it to return the correct value (127).

Fixes: 64470f1b85 ("[CRYPTO] lrw: Liskov Rivest Wagner, a tweakable narrow block cipher mode")
Cc: <stable@vger.kernel.org> # 2.6.20+
Reported-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ondrej Mosnacek 2018-09-13 10:51:31 +02:00 committed by Herbert Xu
parent 331351f89c
commit fbe1a850b3
1 changed files with 6 additions and 1 deletions
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7
crypto/lrw.c
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@ -143,7 +143,12 @@ static inline int get_index128(be128 *block)
return x + ffz(val);
}
return x;
/*
* If we get here, then x == 128 and we are incrementing the counter
* from all ones to all zeros. This means we must return index 127, i.e.
* the one corresponding to key2*{ 1,...,1 }.
*/
return 127;
}
static int post_crypt(struct skcipher_request *req)