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[23.128.96.35]) by mx.google.com with ESMTPS id bq8-20020a056a02044800b005af868c0041si288806pgb.320.2023.10.16.15.05.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Oct 2023 15:05:54 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.35 as permitted sender) client-ip=23.128.96.35; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b="N0fXqiC/"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.35 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by groat.vger.email (Postfix) with ESMTP id 6098980530D8; Mon, 16 Oct 2023 15:05:52 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at groat.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233384AbjJPWFh (ORCPT + 18 others); Mon, 16 Oct 2023 18:05:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52796 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231955AbjJPWFd (ORCPT ); Mon, 16 Oct 2023 18:05:33 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D3829B; Mon, 16 Oct 2023 15:05:32 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B055DC433C8; Mon, 16 Oct 2023 22:05:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697493932; bh=yehbNpyhrwY+5OKnAwXS4+SAIG7u6g3BmUMck9Il2jw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=N0fXqiC/U/SkvoRP9HJgm0THGVBbiF6IhO5dpFY+zdoiIe/ZBAvJpbXJvU6lUGJir NuT9fgiYBvwwFQu2nAXYUWoIMeFe6A4M34JYdACEEgi1zJmHnfW6PhJESPRHgE/5B7 R6h41oq7jkuwITcR03Dk4Al1fMznT61PSovToKBbclkM7RLbfXcLi7sLlAEKgFvD2a 7Lnyy7jLPUkkW+sqopflFD59dZ1gSkWFs/dIsgBjlXdRCArOCIpAWMTsv/St6lqH+A nDgn2KuKu4WOPRNGhjJNI+fFK2N96j/YW2kWDVQep6tWqGAuVHoevDH0N7FzvPzo45 FVt3PX1jkyPrQ== Date: Mon, 16 Oct 2023 16:05:27 -0600 From: "Gustavo A. R. Silva" To: Michael Turquette , Stephen Boyd , Nobuhiro Iwamatsu Cc: Kees Cook , linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org Subject: [PATCH v2 1/2][next] clk: visconti: Fix undefined behavior bug in struct visconti_pll_provider Message-ID: <57a831d94ee2b3889b11525d4ad500356f89576f.1697492890.git.gustavoars@kernel.org> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-1.2 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on groat.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (groat.vger.email [0.0.0.0]); Mon, 16 Oct 2023 15:05:52 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1779951421258322471 X-GMAIL-MSGID: 1779951421258322471 `struct clk_hw_onecell_data` is a flexible structure, which means that it contains flexible-array member at the bottom, in this case array `hws`: include/linux/clk-provider.h: 1380 struct clk_hw_onecell_data { 1381 unsigned int num; 1382 struct clk_hw *hws[] __counted_by(num); 1383 }; This could potentially lead to an overwrite of the objects following `clk_data` in `struct visconti_pll_provider`, in this case `struct device_node *node;`, at run-time: drivers/clk/visconti/pll.h: 16 struct visconti_pll_provider { 17 void __iomem *reg_base; 18 struct clk_hw_onecell_data clk_data; 19 struct device_node *node; 20 }; Notice that a total of 56 bytes are allocated for flexible-array `hws` at line 328. See below: include/dt-bindings/clock/toshiba,tmpv770x.h: 14 #define TMPV770X_NR_PLL 7 drivers/clk/visconti/pll-tmpv770x.c: 69 ctx = visconti_init_pll(np, reg_base, TMPV770X_NR_PLL); drivers/clk/visconti/pll.c: 321 struct visconti_pll_provider * __init visconti_init_pll(struct device_node *np, 322 void __iomem *base, 323 unsigned long nr_plls) 324 { 325 struct visconti_pll_provider *ctx; ... 328 ctx = kzalloc(struct_size(ctx, clk_data.hws, nr_plls), GFP_KERNEL); `struct_size(ctx, clk_data.hws, nr_plls)` above translates to sizeof(struct visconti_pll_provider) + sizeof(struct clk_hw *) * 7 == 24 + 8 * 7 == 24 + 56 ^^^^ | allocated bytes for flex array `hws` $ pahole -C visconti_pll_provider drivers/clk/visconti/pll.o struct visconti_pll_provider { void * reg_base; /* 0 8 */ struct clk_hw_onecell_data clk_data; /* 8 8 */ struct device_node * node; /* 16 8 */ /* size: 24, cachelines: 1, members: 3 */ /* last cacheline: 24 bytes */ }; And then, after the allocation, some data is written into all members of `struct visconti_pll_provider`: 332 for (i = 0; i < nr_plls; ++i) 333 ctx->clk_data.hws[i] = ERR_PTR(-ENOENT); 334 335 ctx->node = np; 336 ctx->reg_base = base; 337 ctx->clk_data.num = nr_plls; Fix all these by placing the declaration of object `clk_data` at the end of `struct visconti_pll_provider`. Also, add a comment to make it clear that this object must always be last in the structure, and prevent this bug from being introduced again in the future. -Wflex-array-member-not-at-end is coming in GCC-14, and we are getting ready to enable it globally. Fixes: b4cbe606dc36 ("clk: visconti: Add support common clock driver and reset driver") Cc: stable@vger.kernel.org Reviewed-by: Kees Cook Acked-by: Nobuhiro Iwamatsu Signed-off-by: Gustavo A. R. Silva --- Changes in v2: - Mention -Wflex-array-member-not-at-end in the changelog text. v1: - Link: https://lore.kernel.org/linux-hardening/0a59a721d54b557076cc94eabeb694d463773204.1697076650.git.gustavoars@kernel.org/ drivers/clk/visconti/pll.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/clk/visconti/pll.h b/drivers/clk/visconti/pll.h index 01d07f1bf01b..c4bd40676da4 100644 --- a/drivers/clk/visconti/pll.h +++ b/drivers/clk/visconti/pll.h @@ -15,8 +15,10 @@ struct visconti_pll_provider { void __iomem *reg_base; - struct clk_hw_onecell_data clk_data; struct device_node *node; + + /* Must be last */ + struct clk_hw_onecell_data clk_data; }; #define VISCONTI_PLL_RATE(_rate, _dacen, _dsmen, \ From patchwork Mon Oct 16 22:06:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. 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[23.128.96.31]) by mx.google.com with ESMTPS id fb10-20020a056a002d8a00b006bd8c5a3b49si154482pfb.90.2023.10.16.15.06.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Oct 2023 15:06:37 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) client-ip=23.128.96.31; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=Ub0BOQHx; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by morse.vger.email (Postfix) with ESMTP id CCF9D802076F; Mon, 16 Oct 2023 15:06:34 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at morse.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233384AbjJPWGW (ORCPT + 18 others); Mon, 16 Oct 2023 18:06:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231955AbjJPWGV (ORCPT ); Mon, 16 Oct 2023 18:06:21 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 82A20A1; Mon, 16 Oct 2023 15:06:20 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B94CDC433C7; Mon, 16 Oct 2023 22:06:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697493980; bh=D7fdEpe0zShD1pFuLK68iJJXBS2qGwVgntab6FWqrjo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Ub0BOQHxbWbUL85k9CgeLDCVNKg+n4jXSewv2gYqW1hfR3aBKTBygdAWyh75PAjOW jxg8DoU0PVbfCtkElQZVFZhb+qZ0dHh/NM3NNWXtsgMFMEDTQvpiiaSWoqczCfTNNv KWG92ncXKedXiJKitRh4LxKowpJicMN50Gik79sg4/ZLAnuVbCymw+Npe8nTmRE4rF QQ68eBToPSHUGgVEMlMFAimZYnXuF9hQ+U2O5FMrPuoVmUK5IV4MqHayLzhJF6L4qf tXNXSQJriezup5YH64Mfc7OMl+GsOyUjow+VZIAUKCoVJ6PRPrqb8IjJKPcZ2Khqde GtamlmfPp70ug== Date: Mon, 16 Oct 2023 16:06:16 -0600 From: "Gustavo A. R. Silva" To: Michael Turquette , Stephen Boyd , Nobuhiro Iwamatsu Cc: Kees Cook , linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org Subject: [PATCH v2 2/2][next] clk: visconti: Add bounds-checking coverage for struct visconti_pll_provider Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-1.2 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on morse.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (morse.vger.email [0.0.0.0]); Mon, 16 Oct 2023 15:06:34 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1779951466501707129 X-GMAIL-MSGID: 1779951466501707129 In order to gain the bounds-checking coverage that __counted_by provides to flexible-array members at run-time via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions), we must make sure that the counter member, in this particular case `num`, is updated before the first access to the flex-array member, in this particular case array `hws`. See below: commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by") introduced `__counted_by` for `struct clk_hw_onecell_data` together with changes to relocate some of assignments of counter `num` before `hws` is accessed: include/linux/clk-provider.h: 1380 struct clk_hw_onecell_data { 1381 unsigned int num; 1382 struct clk_hw *hws[] __counted_by(num); 1383 }; However, this structure is used as a member in other structs, in this case in `struct visconti_pll_provider`: drivers/clk/visconti/pll.h: 16 struct visconti_pll_provider { 17 void __iomem *reg_base; 18 struct device_node *node; 19 20 /* Must be last */ 21 struct clk_hw_onecell_data clk_data; 22 }; Hence, we need to move the assignments to `ctx->clk_data.num` after allocation for `struct visconti_pll_provider` and before accessing the flexible array `ctx->clk_data.hws`. And, as assignments for all members in `struct visconti_pll_provider` are originally adjacent to each other, relocate all assignments together, so we don't split up `ctx->clk_data.hws = nr_plls` from the rest. :) Reviewed-by: Kees Cook Acked-by: Nobuhiro Iwamatsu Signed-off-by: Gustavo A. R. Silva --- Changes in v2: - None. v1: - Link: https://lore.kernel.org/linux-hardening/675633f7ae9893371d35b238f06fd02a3acffebb.1697076650.git.gustavoars@kernel.org/ drivers/clk/visconti/pll.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/clk/visconti/pll.c b/drivers/clk/visconti/pll.c index 1f3234f22667..e9cd80e085dc 100644 --- a/drivers/clk/visconti/pll.c +++ b/drivers/clk/visconti/pll.c @@ -329,12 +329,12 @@ struct visconti_pll_provider * __init visconti_init_pll(struct device_node *np, if (!ctx) return ERR_PTR(-ENOMEM); - for (i = 0; i < nr_plls; ++i) - ctx->clk_data.hws[i] = ERR_PTR(-ENOENT); - ctx->node = np; ctx->reg_base = base; ctx->clk_data.num = nr_plls; + for (i = 0; i < nr_plls; ++i) + ctx->clk_data.hws[i] = ERR_PTR(-ENOENT); + return ctx; }