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 81E5B42586E; Mon, 17 Aug 2026 14:28:34 +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=1786976915; cv=none; b=BRICipSaTLI8PXG76ddfSXusovl1w/F40twogss5D/DoKxBagVzLuXi7aO/1yJgW0E2hc2gf2QcPMuUiJgjOdv6UNjYfvnFmiF2BeoiYebxRVDa+fT0UjnzcOhIJil8ZkNAa8yer/YkPZ6BT2JG9aIPTsLLHXc+MoJ3LqJZr/XA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786976915; c=relaxed/simple; bh=TS//Sx9aUDGddikzFNjkPVu7Kwr8zQhr4/CbjqAeUY8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WPysom5VZEegyPsk8aba4dvdK4QY/jgIu2f5yaMGqqTC/ISgHd9aqdNvQwPgUy7OlPbtFrWzCtgbOTCulwJHcFxlUEGDs9H0211fRwVoz1N6sVKAzFxpKqWRHq84qvH4Rff/BzxAlMD4eAQ+teW2fOCpDmbWq5b8FaeGlHFcUT4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=uynT9V2b; 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="uynT9V2b" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FE7B1F00A3D; Mon, 17 Aug 2026 14:28:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786976914; bh=01H4swl8+WWP4+4JKlaBCO3ZtzKh0pNHZjOoopjCHRc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=uynT9V2b4RVPXgP/PEmpk/EH371rBethldlOJCLIGD19/A00Cba+1J2peNaQEZUYI st0TRLFdotop7Y1WzZnXuxEUFgeHQ7UXxAovfLTIbvlQJ651ymC8ClJIQ61my+AzP2 5tYYuVh/bCHTieWgdSDqo2kk56gRmUlgt/qTKGyQ= 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 5.15 099/456] rds: drop incoming messages that cross network namespace boundaries Date: Mon, 17 Aug 2026 15:28:09 +0200 Message-ID: <20260817132543.970037215@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132539.792407575@linuxfoundation.org> References: <20260817132539.792407575@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 5.15-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 a316180d3c32ec..7fd77e1b4fe71c 100644 --- a/net/rds/recv.c +++ b/net/rds/recv.c @@ -365,6 +365,21 @@ 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