From fbe1a850b3b1522e9fc22319ccbbcd2ab05328d2 Mon Sep 17 00:00:00 2001
From: Ondrej Mosnacek <omosnace@redhat.com>
Date: Thu, 13 Sep 2018 10:51:31 +0200
Subject: [PATCH] crypto: lrw - Fix out-of bounds access on counter overflow
Git-commit: fbe1a850b3b1522e9fc22319ccbbcd2ab05328d2
Patch-mainline: v4.20-rc1
References: bsc#1051510
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: 64470f1b8510 ("[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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
crypto/lrw.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/crypto/lrw.c b/crypto/lrw.c
index 393a782679c7..5504d1325a56 100644
--- a/crypto/lrw.c
+++ b/crypto/lrw.c
@@ -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)
--
2.19.1