From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E262EB64DD for ; Sun, 16 Jul 2023 19:58:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230392AbjGPT6s (ORCPT ); Sun, 16 Jul 2023 15:58:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58374 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230378AbjGPT6q (ORCPT ); Sun, 16 Jul 2023 15:58:46 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B70BF7 for ; Sun, 16 Jul 2023 12:58:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D568560EB7 for ; Sun, 16 Jul 2023 19:58:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E48CCC433C7; Sun, 16 Jul 2023 19:58:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689537524; bh=IdTIutY4uHBSMNXWSLVDbZbdqRIqKBWykVjlWI9Zypc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=j1ShHMBwDJJZVivBBdIvGzFBfHoqu9RkodxKvs8IbyFh41rtj1y8Yl/ooKVdab9PC 7QDgItz4H/YRHYwgskx/IzxXo/TedhFhMxig6K5zCSaft2UZUwiTFhX575OWxjBEOT MzWpiTUNK55w82t+LWHDVvHANYTfvWwOGp19I33o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yafang Shao , Daniel Borkmann , Song Liu , Jiri Olsa , Sasha Levin Subject: [PATCH 6.4 127/800] bpf: Fix memleak due to fentry attach failure Date: Sun, 16 Jul 2023 21:39:40 +0200 Message-ID: <20230716194952.053775642@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230716194949.099592437@linuxfoundation.org> References: <20230716194949.099592437@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Yafang Shao [ Upstream commit 108598c39eefbedc9882273ac0df96127a629220 ] If it fails to attach fentry, the allocated bpf trampoline image will be left in the system. That can be verified by checking /proc/kallsyms. This meamleak can be verified by a simple bpf program as follows: SEC("fentry/trap_init") int fentry_run() { return 0; } It will fail to attach trap_init because this function is freed after kernel init, and then we can find the trampoline image is left in the system by checking /proc/kallsyms. $ tail /proc/kallsyms ffffffffc0613000 t bpf_trampoline_6442453466_1 [bpf] ffffffffc06c3000 t bpf_trampoline_6442453466_1 [bpf] $ bpftool btf dump file /sys/kernel/btf/vmlinux | grep "FUNC 'trap_init'" [2522] FUNC 'trap_init' type_id=119 linkage=static $ echo $((6442453466 & 0x7fffffff)) 2522 Note that there are two left bpf trampoline images, that is because the libbpf will fallback to raw tracepoint if -EINVAL is returned. Fixes: e21aa341785c ("bpf: Fix fexit trampoline.") Signed-off-by: Yafang Shao Signed-off-by: Daniel Borkmann Acked-by: Song Liu Cc: Jiri Olsa Link: https://lore.kernel.org/bpf/20230515130849.57502-2-laoar.shao@gmail.com Signed-off-by: Sasha Levin --- kernel/bpf/trampoline.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 84850e66ce3d6..78acf28d48732 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -251,11 +251,8 @@ bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_a return tlinks; } -static void __bpf_tramp_image_put_deferred(struct work_struct *work) +static void bpf_tramp_image_free(struct bpf_tramp_image *im) { - struct bpf_tramp_image *im; - - im = container_of(work, struct bpf_tramp_image, work); bpf_image_ksym_del(&im->ksym); bpf_jit_free_exec(im->image); bpf_jit_uncharge_modmem(PAGE_SIZE); @@ -263,6 +260,14 @@ static void __bpf_tramp_image_put_deferred(struct work_struct *work) kfree_rcu(im, rcu); } +static void __bpf_tramp_image_put_deferred(struct work_struct *work) +{ + struct bpf_tramp_image *im; + + im = container_of(work, struct bpf_tramp_image, work); + bpf_tramp_image_free(im); +} + /* callback, fexit step 3 or fentry step 2 */ static void __bpf_tramp_image_put_rcu(struct rcu_head *rcu) { @@ -437,7 +442,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut &tr->func.model, tr->flags, tlinks, tr->func.addr); if (err < 0) - goto out; + goto out_free; set_memory_rox((long)im->image, 1); @@ -466,7 +471,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut } #endif if (err) - goto out; + goto out_free; if (tr->cur_image) bpf_tramp_image_put(tr->cur_image); @@ -477,6 +482,10 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut tr->flags = orig_flags; kfree(tlinks); return err; + +out_free: + bpf_tramp_image_free(im); + goto out; } static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog) -- 2.39.2