linux-kernel - [PATCH][next] tls: Use size_add() in call to struct

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Message-ID: <ZQSspmE8Ww8/UNkH@work>
Date:   Fri, 15 Sep 2023 13:12:38 -0600
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Boris Pismenny <borisp@...dia.com>,
        John Fastabend <john.fastabend@...il.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        linux-hardening@...r.kernel.org
Subject: [PATCH][next] tls: Use size_add() in call to struct_size()

If, for any reason, the open-coded arithmetic causes a wraparound,
the protection that `struct_size()` adds against potential integer
overflows is defeated. Fix this by hardening call to `struct_size()`
with `size_add()`.

Fixes: b89fec54fd61 ("tls: rx: wrap decrypt params in a struct")
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 net/tls/tls_sw.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index d1fc295b83b5..270712b8d391 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -1487,7 +1487,7 @@ static int tls_decrypt_sg(struct sock *sk, struct iov_iter *out_iov,
 	 */
 	aead_size = sizeof(*aead_req) + crypto_aead_reqsize(ctx->aead_recv);
 	aead_size = ALIGN(aead_size, __alignof__(*dctx));
-	mem = kmalloc(aead_size + struct_size(dctx, sg, n_sgin + n_sgout),
+	mem = kmalloc(aead_size + struct_size(dctx, sg, size_add(n_sgin, n_sgout)),
 		      sk->sk_allocation);
 	if (!mem) {
 		err = -ENOMEM;
-- 
2.34.1