Re: [syzbot] [crypto?] KASAN: slab-out-of-bounds Read in arc4_crypt

[Edward Adam Davis]

please test slab-out-of-bounds Read in arc4_crypt

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git 17cb8a20bde6

diff --git a/crypto/lskcipher.c b/crypto/lskcipher.c
index a06008e112f3..f7727698b797 100644
--- a/crypto/lskcipher.c
+++ b/crypto/lskcipher.c
@@ -205,11 +205,19 @@ static int crypto_lskcipher_crypt_sg(struct skcipher_request *req,
 	struct crypto_lskcipher **ctx = crypto_skcipher_ctx(skcipher);
 	u8 *ivs = skcipher_request_ctx(req);
 	struct crypto_lskcipher *tfm = *ctx;
+	struct lskcipher_alg *alg = crypto_lskcipher_alg(tfm);
 	struct skcipher_walk walk;
 	unsigned ivsize;
 	u32 flags;
 	int err;
+	static u8 relen;
 
+	if (!relen) {
+		printk("req: %p, alg: %p, ss: %u, %s\n", req, alg, alg->co.statesize, __func__);
+		*req->__ctx = kzalloc(alg->co.statesize, GFP_KERNEL);
+		req->areqlen += alg->co.statesize;
+		relen = 1;
+	}
 	ivsize = crypto_lskcipher_ivsize(tfm);
 	ivs = PTR_ALIGN(ivs, crypto_skcipher_alignmask(skcipher) + 1);