diff mbox series

[31/64] fortify: Explicitly disable Clang support

Message ID	20210727205855.411487-32-keescook@chromium.org
State	Superseded
Headers	show Return-Path: <netdev-owner@kernel.org> From: Kees Cook <keescook@chromium.org> To: linux-hardening@vger.kernel.org Cc: Kees Cook <keescook@chromium.org>, "Gustavo A. R. Silva" <gustavoars@kernel.org>, Keith Packard <keithpac@amazon.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev, linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com Subject: [PATCH 31/64] fortify: Explicitly disable Clang support Date: Tue, 27 Jul 2021 13:58:22 -0700 Message-Id: <20210727205855.411487-32-keescook@chromium.org> In-Reply-To: <20210727205855.411487-1-keescook@chromium.org> References: <20210727205855.411487-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	Introduce strict memcpy() bounds checking \| expand [00/64] Introduce strict memcpy() bounds checking [01/64] media: omap3isp: Extract struct group for memcpy() region [02/64] mac80211: Use flex-array for radiotap header bitmap [03/64] rpmsg: glink: Replace strncpy() with strscpy_pad() [04/64] stddef: Introduce struct_group() helper macro [05/64] skbuff: Switch structure bounds to struct_group() [06/64] bnxt_en: Use struct_group_attr() for memcpy() region [07/64] staging: rtl8192e: Use struct_group() for memcpy() region [08/64] staging: rtl8192u: Use struct_group() for memcpy() region [09/64] staging: rtl8723bs: Avoid field-overflowing memcpy() [10/64] lib80211: Use struct_group() for memcpy() region [11/64] net/mlx5e: Avoid field-overflowing memcpy() [12/64] mwl8k: Use struct_group() for memcpy() region [13/64] libertas: Use struct_group() for memcpy() region [14/64] libertas_tf: Use struct_group() for memcpy() region [15/64] ipw2x00: Use struct_group() for memcpy() region [16/64] thermal: intel: int340x_thermal: Use struct_group() for memcpy() region [17/64] iommu/amd: Use struct_group() for memcpy() region [18/64] cxgb3: Use struct_group() for memcpy() region [19/64] ip: Use struct_group() for memcpy() regions [20/64] intersil: Use struct_group() for memcpy() region [21/64] cxgb4: Use struct_group() for memcpy() region [22/64] bnx2x: Use struct_group() for memcpy() region [23/64] drm/amd/pm: Use struct_group() for memcpy() region [24/64] staging: wlan-ng: Use struct_group() for memcpy() region [25/64] drm/mga/mga_ioc32: Use struct_group() for memcpy() region [26/64] net/mlx5e: Use struct_group() for memcpy() region [27/64] HID: cp2112: Use struct_group() for memcpy() region [28/64] compiler_types.h: Remove __compiletime_object_size() [29/64] lib/string: Move helper functions out of string.c [30/64] fortify: Move remaining fortify helpers into fortify-string.h [31/64] fortify: Explicitly disable Clang support [32/64] fortify: Add compile-time FORTIFY_SOURCE tests [33/64] lib: Introduce CONFIG_TEST_MEMCPY [34/64] fortify: Detect struct member overflows in memcpy() at compile-time [35/64] fortify: Detect struct member overflows in memmove() at compile-time [36/64] scsi: ibmvscsi: Avoid multi-field memset() overflow by aiming at srp [37/64] string.h: Introduce memset_after() for wiping trailing members/padding [38/64] xfrm: Use memset_after() to clear padding [39/64] mac80211: Use memset_after() to clear tx status [40/64] net: 802: Use memset_after() to clear struct fields [41/64] net: dccp: Use memset_after() for TP zeroing [42/64] net: qede: Use memset_after() for counters [43/64] ath11k: Use memset_after() for clearing queue descriptors [44/64] iw_cxgb4: Use memset_after() for cpl_t5_pass_accept_rpl [45/64] intel_th: msu: Use memset_after() for clearing hw header [46/64] IB/mthca: Use memset_after() for clearing mpt_entry [47/64] btrfs: Use memset_after() to clear end of struct [48/64] drbd: Use struct_group() to zero algs [49/64] cm4000_cs: Use struct_group() to zero struct cm4000_dev region [50/64] KVM: x86: Use struct_group() to zero decode cache [51/64] tracing: Use struct_group() to zero struct trace_iterator [52/64] dm integrity: Use struct_group() to zero struct journal_sector [53/64] HID: roccat: Use struct_group() to zero kone_mouse_event [54/64] ipv6: Use struct_group() to zero rt6_info [55/64] RDMA/mlx5: Use struct_group() to zero struct mlx5_ib_mr [56/64] ethtool: stats: Use struct_group() to clear all stats at once [57/64] netfilter: conntrack: Use struct_group() to zero struct nf_conn [58/64] powerpc: Split memset() to avoid multi-field overflow [59/64] fortify: Detect struct member overflows in memset() at compile-time [60/64] fortify: Work around Clang inlining bugs [61/64] Makefile: Enable -Warray-bounds [62/64] netlink: Avoid false-positive memcpy() warning [63/64] iwlwifi: dbg_ini: Split memcpy() to avoid multi-field write [64/64] fortify: Add run-time WARN for cross-field memcpy()

Commit Message

Kees Cook July 27, 2021, 8:58 p.m. UTC

Clang has never correctly compiled the FORTIFY_SOURCE defenses due to
a couple bugs:

	Eliding inlines with matching __builtin_* names
	https://bugs.llvm.org/show_bug.cgi?id=50322

	Incorrect __builtin_constant_p() of some globals
	https://bugs.llvm.org/show_bug.cgi?id=41459

In the process of making improvements to the FORTIFY_SOURCE defenses, the
first (silent) bug (coincidentally) becomes worked around, but exposes
the latter which breaks the build. As such, Clang must not be used with
CONFIG_FORTIFY_SOURCE until at least latter bug is fixed (in Clang 13),
and the fortify routines have been rearranged.

Update the Kconfig to reflect the reality of the current situation.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 security/Kconfig | 3 +++
 1 file changed, 3 insertions(+)

diff mbox series

Patch

diff --git a/security/Kconfig b/security/Kconfig
index 0ced7fd33e4d..8f0e675e70a4 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -191,6 +191,9 @@  config HARDENED_USERCOPY_PAGESPAN
 config FORTIFY_SOURCE
 	bool "Harden common str/mem functions against buffer overflows"
 	depends on ARCH_HAS_FORTIFY_SOURCE
+	# https://bugs.llvm.org/show_bug.cgi?id=50322
+	# https://bugs.llvm.org/show_bug.cgi?id=41459
+	depends on !CONFIG_CC_IS_CLANG
 	help
 	  Detect overflows of buffers in common string and memory functions
 	  where the compiler can determine and validate the buffer sizes.