From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 73EAB54FA8; Thu, 30 Nov 2023 16:25:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="AaTiRhKq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 920D7C433C7; Thu, 30 Nov 2023 16:25:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1701361552; bh=kag4vTvai0VnroRLRSRf9ysfCxrqkUO5n8gx5S86zUY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AaTiRhKqWXRE4WS+PXk9WsW8XvkNfD3PxIrwrHth9Pj4FPUgrk9ZX+LU4V3vuwMqL Kp5tKi6fhCKUp7udOUa/5eY+wiY3yA3sLOdZCmG7BbDRK3cFoL9aW2q5dcZOU5+GUq KtC/h8QI6npqZ3GnSZ+sqV5XPrwLQixir+czLDig= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+40d43509a099ea756317@syzkaller.appspotmail.com, Jann Horn , Jakub Kicinski Subject: [PATCH 6.6 068/112] tls: fix NULL deref on tls_sw_splice_eof() with empty record Date: Thu, 30 Nov 2023 16:21:55 +0000 Message-ID: <20231130162142.481412522@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231130162140.298098091@linuxfoundation.org> References: <20231130162140.298098091@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jann Horn commit 53f2cb491b500897a619ff6abd72f565933760f0 upstream. syzkaller discovered that if tls_sw_splice_eof() is executed as part of sendfile() when the plaintext/ciphertext sk_msg are empty, the send path gets confused because the empty ciphertext buffer does not have enough space for the encryption overhead. This causes tls_push_record() to go on the `split = true` path (which is only supposed to be used when interacting with an attached BPF program), and then get further confused and hit the tls_merge_open_record() path, which then assumes that there must be at least one populated buffer element, leading to a NULL deref. It is possible to have empty plaintext/ciphertext buffers if we previously bailed from tls_sw_sendmsg_locked() via the tls_trim_both_msgs() path. tls_sw_push_pending_record() already handles this case correctly; let's do the same check in tls_sw_splice_eof(). Fixes: df720d288dbb ("tls/sw: Use splice_eof() to flush") Cc: stable@vger.kernel.org Reported-by: syzbot+40d43509a099ea756317@syzkaller.appspotmail.com Signed-off-by: Jann Horn Link: https://lore.kernel.org/r/20231122214447.675768-1-jannh@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/tls/tls_sw.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index a78e8e722409..316f76187962 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -1232,11 +1232,14 @@ void tls_sw_splice_eof(struct socket *sock) lock_sock(sk); retry: + /* same checks as in tls_sw_push_pending_record() */ rec = ctx->open_rec; if (!rec) goto unlock; msg_pl = &rec->msg_plaintext; + if (msg_pl->sg.size == 0) + goto unlock; /* Check the BPF advisor and perform transmission. */ ret = bpf_exec_tx_verdict(msg_pl, sk, false, TLS_RECORD_TYPE_DATA, -- 2.43.0