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 373B220F88 for ; Fri, 21 Jul 2023 19:06:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ADB50C433C7; Fri, 21 Jul 2023 19:06:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689966409; bh=pK3w8qX/wKMDtR2SGmvczxsFQkQpmfwgx1AmGtRvBZ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XlHZIDcXQBRquwFz3gsm56dpv03Cg9F0zXY9iFj81aCItS4nVjuMkL6uP7ydpab0L da/8kDcQqhSXkk8GhmapsLL8gvaCdtgjulLVACfNrh8HpnjGoUqIl4OUOJhOfoqA92 jbyZx4KxJ3kJCuChDWCi8WWrpXyDzjHrI4GVHXcE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chengfeng Ye , Xin Long , Paolo Abeni , Sasha Levin Subject: [PATCH 5.15 316/532] sctp: fix potential deadlock on &net->sctp.addr_wq_lock Date: Fri, 21 Jul 2023 18:03:40 +0200 Message-ID: <20230721160631.536322677@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230721160614.695323302@linuxfoundation.org> References: <20230721160614.695323302@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Chengfeng Ye [ Upstream commit 6feb37b3b06e9049e20dcf7e23998f92c9c5be9a ] As &net->sctp.addr_wq_lock is also acquired by the timer sctp_addr_wq_timeout_handler() in protocal.c, the same lock acquisition at sctp_auto_asconf_init() seems should disable irq since it is called from sctp_accept() under process context. Possible deadlock scenario: sctp_accept() -> sctp_sock_migrate() -> sctp_auto_asconf_init() -> spin_lock(&net->sctp.addr_wq_lock) -> sctp_addr_wq_timeout_handler() -> spin_lock_bh(&net->sctp.addr_wq_lock); (deadlock here) This flaw was found using an experimental static analysis tool we are developing for irq-related deadlock. The tentative patch fix the potential deadlock by spin_lock_bh(). Signed-off-by: Chengfeng Ye Fixes: 34e5b0118685 ("sctp: delay auto_asconf init until binding the first addr") Acked-by: Xin Long Link: https://lore.kernel.org/r/20230627120340.19432-1-dg573847474@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/sctp/socket.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index ed35d4a4c5253..f10ad80fd6948 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -362,9 +362,9 @@ static void sctp_auto_asconf_init(struct sctp_sock *sp) struct net *net = sock_net(&sp->inet.sk); if (net->sctp.default_auto_asconf) { - spin_lock(&net->sctp.addr_wq_lock); + spin_lock_bh(&net->sctp.addr_wq_lock); list_add_tail(&sp->auto_asconf_list, &net->sctp.auto_asconf_splist); - spin_unlock(&net->sctp.addr_wq_lock); + spin_unlock_bh(&net->sctp.addr_wq_lock); sp->do_auto_asconf = 1; } } -- 2.39.2