linux-kernel - Re: [syzbot] [crypto?] KASAN: slab-out-of-bounds Read in arc4

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Message-ID: <tencent_ED8C99A7EB86C012DA86504993EEC1EECA06@qq.com>
Date: Wed, 20 Dec 2023 14:56:23 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+8ffb0839a24e9c6bfa76@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [crypto?] KASAN: slab-out-of-bounds Read in arc4_crypt

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/algif_skcipher.c b/crypto/algif_skcipher.c
index 02cea2149504..e1f44dc60e4a 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -106,7 +106,7 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 	struct af_alg_async_req *areq;
 	unsigned cflags = 0;
 	int err = 0;
-	size_t len = 0;
+	size_t len = 0, aqlen;
 
 	if (!ctx->init || (ctx->more && ctx->used < bs)) {
 		err = af_alg_wait_for_data(sk, flags, bs);
@@ -115,11 +115,13 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 	}
 
 	/* Allocate cipher request for current operation. */
-	areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
-				     crypto_skcipher_reqsize(tfm));
+	aqlen = sizeof(struct af_alg_async_req) + crypto_skcipher_reqsize(tfm);
+	areq = af_alg_alloc_areq(sk, aqlen + 1032);
 	if (IS_ERR(areq))
 		return PTR_ERR(areq);
 
+	printk("req: %p, areqlen: %u, al: %u, %s\n", 
+		&areq->cra_u.skcipher_req, areq->areqlen, aqlen, __func__);
 	/* convert iovecs of output buffers into RX SGL */
 	err = af_alg_get_rsgl(sk, msg, flags, areq, ctx->used, &len);
 	if (err)