From patchwork Tue Nov 8 05:11:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: wangyufen X-Patchwork-Id: 13035857 X-Patchwork-Delegate: bpf@iogearbox.net 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 AE9ABC43217 for ; Tue, 8 Nov 2022 04:51:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232847AbiKHEvX (ORCPT ); Mon, 7 Nov 2022 23:51:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56556 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232911AbiKHEvW (ORCPT ); Mon, 7 Nov 2022 23:51:22 -0500 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 688C915733; Mon, 7 Nov 2022 20:51:07 -0800 (PST) Received: from canpemm500010.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4N5wf60s3Nz15MSf; Tue, 8 Nov 2022 12:50:54 +0800 (CST) Received: from localhost.localdomain (10.175.112.70) by canpemm500010.china.huawei.com (7.192.105.118) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 8 Nov 2022 12:51:04 +0800 From: Wang Yufen To: , CC: , , , , , , Subject: [PATCH bpf v4] bpf: Fix memory leaks in __check_func_call Date: Tue, 8 Nov 2022 13:11:31 +0800 Message-ID: <1667884291-15666-1-git-send-email-wangyufen@huawei.com> X-Mailer: git-send-email 1.8.3.1 MIME-Version: 1.0 X-Originating-IP: [10.175.112.70] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500010.china.huawei.com (7.192.105.118) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net kmemleak reports this issue: unreferenced object 0xffff88817139d000 (size 2048): comm "test_progs", pid 33246, jiffies 4307381979 (age 45851.820s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<0000000045f075f0>] kmalloc_trace+0x27/0xa0 [<0000000098b7c90a>] __check_func_call+0x316/0x1230 [<00000000b4c3c403>] check_helper_call+0x172e/0x4700 [<00000000aa3875b7>] do_check+0x21d8/0x45e0 [<000000001147357b>] do_check_common+0x767/0xaf0 [<00000000b5a595b4>] bpf_check+0x43e3/0x5bc0 [<0000000011e391b1>] bpf_prog_load+0xf26/0x1940 [<0000000007f765c0>] __sys_bpf+0xd2c/0x3650 [<00000000839815d6>] __x64_sys_bpf+0x75/0xc0 [<00000000946ee250>] do_syscall_64+0x3b/0x90 [<0000000000506b7f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd The root case here is: In function prepare_func_exit(), the callee is not released in the abnormal scenario after "state->curframe--;". To fix, move "state->curframe--;" to the very bottom of the function, right when we free callee and reset frame[] pointer to NULL, as Andrii suggested. In addition, function __check_func_call() has a similar problem. In the abnormal scenario before "state->curframe++;", the callee also should be released by free_func_state(). Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") Fixes: fd978bf7fd31 ("bpf: Add reference tracking to verifier") Signed-off-by: Wang Yufen --- kernel/bpf/verifier.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7f0a9f6..34d8848 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6736,11 +6736,11 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn /* Transfer references to the callee */ err = copy_reference_state(callee, caller); if (err) - return err; + goto err_out; err = set_callee_state_cb(env, caller, callee, *insn_idx); if (err) - return err; + goto err_out; clear_caller_saved_regs(env, caller->regs); @@ -6757,6 +6757,11 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn print_verifier_state(env, callee, true); } return 0; + +err_out: + free_func_state(callee); + state->frame[state->curframe + 1] = NULL; + return err; } int map_set_for_each_callback_args(struct bpf_verifier_env *env, @@ -6970,8 +6975,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) return -EINVAL; } - state->curframe--; - caller = state->frame[state->curframe]; + caller = state->frame[state->curframe - 1]; if (callee->in_callback_fn) { /* enforce R0 return value range [0, 1]. */ struct tnum range = callee->callback_ret_range; @@ -7010,7 +7014,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) } /* clear everything in the callee */ free_func_state(callee); - state->frame[state->curframe + 1] = NULL; + state->frame[state->curframe--] = NULL; return 0; }