From e86f4842f84a4494227aa4d1ab76acb68d86fb1a Mon Sep 17 00:00:00 2001 From: Ondrej Mosnacek Date: Thu, 13 Sep 2018 10:51:31 +0200 Subject: [PATCH] crypto: lrw - Fix out-of bounds access on counter overflow commit fbe1a850b3b1522e9fc22319ccbbcd2ab05328d2 upstream. 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: # 2.6.20+ Reported-by: Eric Biggers Signed-off-by: Ondrej Mosnacek Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- crypto/lrw.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/crypto/lrw.c b/crypto/lrw.c index fdba6dd..886f91f 100644 --- a/crypto/lrw.c +++ b/crypto/lrw.c @@ -139,7 +139,12 @@ 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) -- 2.7.4