From nobody Thu May 7 20:14:54 2026 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 1E83CC433F5 for ; Thu, 19 May 2022 12:55:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238217AbiESMzg (ORCPT ); Thu, 19 May 2022 08:55:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234713AbiESMz3 (ORCPT ); Thu, 19 May 2022 08:55:29 -0400 Received: from mail-pg1-x536.google.com (mail-pg1-x536.google.com [IPv6:2607:f8b0:4864:20::536]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46D1EA7E36 for ; Thu, 19 May 2022 05:55:28 -0700 (PDT) Received: by mail-pg1-x536.google.com with SMTP id 137so4993292pgb.5 for ; Thu, 19 May 2022 05:55:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=XiUsRi0TcKngRpQ/Aq2tkPZeo5Erutd/MtmCgm/5bYU=; b=MRvUskMS0dP9aYF0X75Mw2BIhDXmrUI5V2pM7+rkEZ158WuT9cZe4IexXcTj+ckM6i +iz8Rx1U7C3CnSE5DvvQPv9cnm7wPAnYi3p07DcDBhtTMuiZ6trrjNVBdEKWUXgBJm0D wxQLG3pJmHYv6LiStLin3J3zLFhidhzdyRuA2VtubHUeAfgtUKMsjeDCSokJoaLDnLke IGWzmoAgd9tqR/0J3vNW2mQJqh3Sg2aEdgo99EpPShPJhNszGRPIULjKkfTpChErPPuG sURwiVhnCKdDino+ptabRTeyYJwwSGLrNzYflyG8C/0073CdhdU+WnYgekHMXwL8uKt9 7X2Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=XiUsRi0TcKngRpQ/Aq2tkPZeo5Erutd/MtmCgm/5bYU=; b=15n+9sFYPUQn+ENWMPyo2S0PtPYEFYilsYvRR7NgzlMhqcjzaTGZ9YwYZrskzjGsqe 1UbYaFToelKmXFBECJumHdmXXnEE5aadMDOESGM5hcoz1CuceehaSB4nJf6W33BzRI1v BoWeuWDVqJknYICHjBS6CNb5rX9ZHwaWFn+rPjIrOPZsautN6S6Pr6lKILAHAEIyz9gl /AmO9hQujihJLRxUUNtYzMPGfZtIF97kA1fWrOH+N5YyhLmiugQIpoaZMLhxZqIn7I6k 5fWybUGH5+2q4XphEL0HAflTbq+xxXRk+0T8RY6T7mxD3VU8twZBqYfvXy0ifOIsYy25 sZ6w== X-Gm-Message-State: AOAM5336tLiDOeNVPuMEXc/jS0P1Fpx+v+qf6+Bb255obU34Gd4ELnbc vO9apW//o7mMicOHGsue5Ql6DpFms2TI/A== X-Google-Smtp-Source: ABdhPJxMmOwhWa8SHa/gVmsNZFJ9NCopj+W+34thmpChLqFM/4MyZoVb5YqSIWIq+rP6kZLzTnkSCA== X-Received: by 2002:a05:6a00:140f:b0:4e0:6995:9c48 with SMTP id l15-20020a056a00140f00b004e069959c48mr4568784pfu.59.1652964927356; Thu, 19 May 2022 05:55:27 -0700 (PDT) Received: from FVFYT0MHHV2J.bytedance.net ([139.177.225.250]) by smtp.gmail.com with ESMTPSA id iz10-20020a170902ef8a00b0015e8d4eb1ddsm3664659plb.39.2022.05.19.05.55.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 May 2022 05:55:27 -0700 (PDT) From: Muchun Song To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: duanxiongchun@bytedance.com, smuchun@gmail.com, Muchun Song , Luis Chamberlain , Kees Cook , Iurii Zaikin Subject: [PATCH] sysctl: handle table->maxlen properly for proc_dobool Date: Thu, 19 May 2022 20:55:05 +0800 Message-Id: <20220519125505.92400-1-songmuchun@bytedance.com> X-Mailer: git-send-email 2.32.1 (Apple Git-133) MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Setting ->proc_handler to proc_dobool at the same time setting ->maxlen to sizeof(int) is counter-intuitive, it is easy to make mistakes. For robustness, fix it by handling able->maxlen properly for proc_dobool in __do_proc_dointvec(). Signed-off-by: Muchun Song Cc: Luis Chamberlain Cc: Kees Cook Cc: Iurii Zaikin --- fs/lockd/svc.c | 2 +- kernel/sysctl.c | 22 ++++++++++++---------- 2 files changed, 13 insertions(+), 11 deletions(-) diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c index 59ef8a1f843f..6e48ee787f49 100644 --- a/fs/lockd/svc.c +++ b/fs/lockd/svc.c @@ -496,7 +496,7 @@ static struct ctl_table nlm_sysctls[] =3D { { .procname =3D "nsm_use_hostnames", .data =3D &nsm_use_hostnames, - .maxlen =3D sizeof(int), + .maxlen =3D sizeof(nsm_use_hostnames), .mode =3D 0644, .proc_handler =3D proc_dobool, }, diff --git a/kernel/sysctl.c b/kernel/sysctl.c index e52b6e372c60..353fb9093012 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -428,6 +428,8 @@ static int do_proc_dobool_conv(bool *negp, unsigned lon= g *lvalp, int write, void *data) { if (write) { + if (*negp || (*lvalp !=3D 0 && *lvalp !=3D 1)) + return -EINVAL; *(bool *)valp =3D *lvalp; } else { int val =3D *(bool *)valp; @@ -489,17 +491,17 @@ static int __do_proc_dointvec(void *tbl_data, struct = ctl_table *table, int write, void *data), void *data) { - int *i, vleft, first =3D 1, err =3D 0; + int vleft, first =3D 1, err =3D 0, size; size_t left; char *p; -=09 + if (!tbl_data || !table->maxlen || !*lenp || (*ppos && !write)) { *lenp =3D 0; return 0; } -=09 - i =3D (int *) tbl_data; - vleft =3D table->maxlen / sizeof(*i); + + size =3D conv =3D=3D do_proc_dobool_conv ? sizeof(bool) : sizeof(int); + vleft =3D table->maxlen / size; left =3D *lenp; =20 if (!conv) @@ -514,7 +516,7 @@ static int __do_proc_dointvec(void *tbl_data, struct ct= l_table *table, p =3D buffer; } =20 - for (; left && vleft--; i++, first=3D0) { + for (; left && vleft--; tbl_data =3D (char *)tbl_data + size, first=3D0) { unsigned long lval; bool neg; =20 @@ -528,12 +530,12 @@ static int __do_proc_dointvec(void *tbl_data, struct = ctl_table *table, sizeof(proc_wspace_sep), NULL); if (err) break; - if (conv(&neg, &lval, i, 1, data)) { + if (conv(&neg, &lval, tbl_data, 1, data)) { err =3D -EINVAL; break; } } else { - if (conv(&neg, &lval, i, 0, data)) { + if (conv(&neg, &lval, tbl_data, 0, data)) { err =3D -EINVAL; break; } @@ -708,8 +710,8 @@ int do_proc_douintvec(struct ctl_table *table, int writ= e, * @lenp: the size of the user buffer * @ppos: file position * - * Reads/writes up to table->maxlen/sizeof(unsigned int) integer - * values from/to the user buffer, treated as an ASCII string. + * Reads/writes up to table->maxlen/sizeof(bool) bool values from/to + * the user buffer, treated as an ASCII string. * * Returns 0 on success. */ --=20 2.11.0