From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6FB2B446C08; Thu, 30 Jul 2026 15:05:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423937; cv=none; b=tb4NKJe8P7HGU1luSjfGilVwv5N6HqbISi5/7eiQrrF3IJuGdOYS6fFiDD1NNyv0y7MOz95YpphPKves53DbL5/hZOei2Pxxr2EPrZbcdtG4KRFhYLVRNuGtBKlIzO97991vV8I5V7HI4SXfh+Qv7nQZHuqpoojovfl4FdB1BXY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423937; c=relaxed/simple; bh=KfLU1SBw0tP6lsKzdSYf+0rXjb5bygHI1JQAjCiDIxU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MY3Bp5PB87AZNt8jDlUhvnDq1PH/O0L28bTb5da2uzT5gwpM4ksoDHjurAIF6IQrbj6zExxcOXSq1bFT/4Y9rumZVgka2ne+y5Cd4Lq3+S9bxN+m9rX01SMzkIm0E2X3/UFvNTnxrRbDXUdjwezLN5R3EQS8etsahceiWiQkqFA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mWszPfXl; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="mWszPfXl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 92D051F00ACF; Thu, 30 Jul 2026 15:05:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785423936; bh=nv+fAnjlIvlkeRMAy6ES/txUculFCrqNYSIH3uJEVaE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mWszPfXlbJiGAhqMDNKcGnZmPzxoZcppr59ckK0vYNsWRksuDXXXyXQdy9yb8nXU/ rJkFlB1STRHrHHGFMZ3hTiVr41rmE4GOngcmhO5uEQT5xCQ9BctYDgTsqOowtgejmU IP021ZFVr42Fauloj7VNnZqlxw39Yvoi8LexM3WE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Aldo Ariel Panzardo , Allison Henderson , Paolo Abeni , Sasha Levin Subject: [PATCH 6.18 216/675] rds: drop incoming messages that cross network namespace boundaries Date: Thu, 30 Jul 2026 16:09:06 +0200 Message-ID: <20260730141449.734835873@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Aldo Ariel Panzardo [ Upstream commit 5521ae71e32a8069ed4ca6e792179dc57bc43ab2 ] rds_find_bound() looks up the destination socket using a global rhashtable keyed solely on (addr, port, scope_id). Network namespaces are not part of the key, so a sender in netns A can deliver an incoming message (inc) to a socket that lives in a different netns B. When this happens, inc->i_conn points to an rds_connection whose c_net is netns A, but the receiving rs lives in netns B. Once the child process that created netns A exits, cleanup_net() calls rds_loop_exit_net() -> rds_loop_kill_conns() -> rds_conn_destroy(), freeing that connection. If the survivor socket in netns B still holds the inc, any subsequent dereference of inc->i_conn is a use-after-free. There are two dangerous sites in rds_clear_recv_queue(): 1. inc->i_conn->c_lcong (offset 88 of freed rds_connection, size 200) read via rds_recv_rcvbuf_delta() -- confirmed by KASAN. 2. inc->i_conn->c_trans->inc_free(inc) (function pointer at offset 80) called via rds_inc_put() when the inc refcount reaches zero -- same race window, potential call-through-freed-object primitive. The bug is reachable from unprivileged user namespaces (CLONE_NEWUSER + CLONE_NEWNET), available since Linux 3.8. Fix this by rejecting the delivery in rds_recv_incoming() when the socket returned by rds_find_bound() belongs to a different network namespace than the connection that carried the message. Use the existing rds_conn_net() / sock_net() helpers and net_eq() for the comparison. Fixes: c809195f5523 ("rds: clean up loopback rds_connections on netns deletion") Signed-off-by: Aldo Ariel Panzardo Reviewed-by: Allison Henderson Tested-by: Allison Henderson Signed-off-by: Allison Henderson Link: https://patch.msgid.link/20260708024314.601139-1-achender@kernel.org Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/rds/recv.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/net/rds/recv.c b/net/rds/recv.c index 66205d6924bf3d..4b12fa4f1e7869 100644 --- a/net/rds/recv.c +++ b/net/rds/recv.c @@ -366,6 +366,21 @@ void rds_recv_incoming(struct rds_connection *conn, struct in6_addr *saddr, goto out; } + /* + * rds_find_bound() uses a global (netns-agnostic) hash table. + * An RDS connection created in netns A can match a socket bound + * in the init netns, delivering inc cross-netns with inc->i_conn + * pointing into netns A. When cleanup_net() then frees that conn, + * any subsequent dereference of inc->i_conn is a use-after-free. + * Drop the inc if the receiving socket lives in a different netns. + */ + if (!net_eq(sock_net(rds_rs_to_sk(rs)), rds_conn_net(conn))) { + rds_stats_inc(s_recv_drop_no_sock); + rds_sock_put(rs); + rs = NULL; + goto out; + } + /* Process extension headers */ rds_recv_incoming_exthdrs(inc, rs); -- 2.53.0