From patchwork Thu Oct 12 02:17:36 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 13418153 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 F2320CDB465 for ; Thu, 12 Oct 2023 02:17:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234053AbjJLCRl (ORCPT ); Wed, 11 Oct 2023 22:17:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232321AbjJLCRl (ORCPT ); Wed, 11 Oct 2023 22:17:41 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F92798; Wed, 11 Oct 2023 19:17:40 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95431C433C7; Thu, 12 Oct 2023 02:17:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697077059; bh=GWfBuFj92ThQwSFoJGmNN5lq51idDCBd7SCsrd8jqGY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Lg46DKy1m+EfsDO0AGJ0OVNV9j5iFYUVB0G74TlBT1kJjl1S7SeV/Si8q6QJi8WTd z7s6r3dh7LjvKosUTRg7Q6NWSKOyYAPjG4+eIbnCkHYFLnN0hHeIz8v7xHi/L2rodO 8xw39+Rh9BozeGiCu7iikMCLX8o3V7KceKkGGXDVvW9aehv0x6/vxaY7yDuvr72eGV 74MAXDgix+jX59VtehzPAlnmIDNDhOtKwh0UPC6I8oF4LtlBoz4aerGAQG8AOWxNrI ZF2WWBFxN6dNdPWALN4FUZY+2sfWxmd98OEIjc8KlhUhUiO6eZn9QYUukkITVSbOq7 CAWQ1R5FBn5GA== Date: Wed, 11 Oct 2023 20:17:36 -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 1/2][next] clk: visconti: Fix undefined behavior bug in struct visconti_pll_provider Message-ID: <0a59a721d54b557076cc94eabeb694d463773204.1697076650.git.gustavoars@kernel.org> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org `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. Fixes: b4cbe606dc36 ("clk: visconti: Add support common clock driver and reset driver") Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva Reviewed-by: Kees Cook Acked-by: Nobuhiro Iwamatsu --- 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 Thu Oct 12 02:18:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 13418154 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 27D8ACDB465 for ; Thu, 12 Oct 2023 02:18:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233989AbjJLCSv (ORCPT ); Wed, 11 Oct 2023 22:18:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54466 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233797AbjJLCSu (ORCPT ); Wed, 11 Oct 2023 22:18:50 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6949FB6; Wed, 11 Oct 2023 19:18:49 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5BE0C433C8; Thu, 12 Oct 2023 02:18:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697077129; bh=NePGQwBKuxNkoa39buLkrVoRes9zHH25Dkf23OgpCjM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UVhiz6z/97OOSugRxlauh+TMHfJufV+mWRoRMD2YXt8tyY1UPkDiYTakb/Bx/GamR MigEfZyD9OMed1dDbdfM87yNyzEAliLbMH98/oI6B1+taXYd2rbvFvrdy9xWhe2+A+ SIGWUgGYJx7/XsjBDTpzj3OY2ODYJ1iPYFsHmZjRTqM+78PHUrfH2QcgRaxU/dKcv0 vpsC8wp2NPgL8NzJigOm+oTjYH/L459BACaMAgKkPqX6tj7kiFvdTzQ+ckpjSM53O8 kzGsqRjWfpOSEngRJbl4wenw7qBM6A3F+VxRRGTuEJr+f7faCg2DKIFtiR+ZnyPFff ysV2ArQKTDviA== Date: Wed, 11 Oct 2023 20:18:45 -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 2/2][next] clk: visconti: Add bounds-checking coverage for struct visconti_pll_provider Message-ID: <675633f7ae9893371d35b238f06fd02a3acffebb.1697076650.git.gustavoars@kernel.org> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org 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. :) Signed-off-by: Gustavo A. R. Silva Reviewed-by: Kees Cook Acked-by: Nobuhiro Iwamatsu --- 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; }