From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D050621019E; Wed, 23 Oct 2024 14:32:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729693945; cv=none; b=ENAP/DxeTkzKChDAjY+eETQy8VpdoaLjNTAXCUC3MTkrpHIoA5RCse0kd9qKlejFcY04YfIXRr9sbfZRyBnVvgHh1vetBfJvSd7JlbgQ7E7OWTm92AAAzqWTaCJziBFHZ+LSHCL+45kvZe+I7+Jl7hnnK6VvwOtDqkMdj1Yu4E0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729693945; c=relaxed/simple; bh=imG7XOhpPcLebJiLUrkf6tWJV5AXos0CtdMWmfyQNak=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bT7j+IEYuLwxp3IJti+BuI9iEu+lqQK31VmGj/wHn85LQf7n6WMjEipAaWvihUW7UdS4aLJjBTy7x60CJB7zRhCcQrjQSnTYVvbMyD+o1a8tlbDvoqL+Sm2/yZwN8byHHHw/57HNHQrEm/YQ0ZLSpZLNfnDucaHk6TbrBan0Jzk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZcVPBl07; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZcVPBl07" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7FB62C4CEE4; Wed, 23 Oct 2024 14:32:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729693945; bh=imG7XOhpPcLebJiLUrkf6tWJV5AXos0CtdMWmfyQNak=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZcVPBl07cItKL4rdhMn/OT/Tgq2UXNmVOrYbJBw3wpzPu9hfTs8/xmUJNNFTn/spj vYMmKZDOpEzaOSnlprw7PujDuW3B5mgKHJeCepHz2Ld7Q9RhIau9jnoaFpg8PrNSfQ 4dgOy1hP4LXwkGtsAZszvJYOLLxkDAWZXRTls4HOdkXhY5eCxaACyh5Y8yRWnAQ4v7 SVbU2fYqdYxYdELEh/nKKm/yW9K3IzBpsZb4qvU0n75/qJtgyOzztx4EWkCDaAUB7p 45M4POFQXqWykgg99jX7tFtwK3sKipWHSieE1+1yXkPtSaGEYPJlRDaTt86NB2VpKq gpXxtGepELmlQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Will Deacon , Andrey Konovalov , Mark Rutland , syzbot+908886656a02769af987@syzkaller.appspotmail.com, Sasha Levin , ryabinin.a.a@gmail.com, nathan@kernel.org, kasan-dev@googlegroups.com, llvm@lists.linux.dev Subject: [PATCH AUTOSEL 6.1 14/17] kasan: Disable Software Tag-Based KASAN with GCC Date: Wed, 23 Oct 2024 10:31:53 -0400 Message-ID: <20241023143202.2981992-14-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241023143202.2981992-1-sashal@kernel.org> References: <20241023143202.2981992-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.1.114 Content-Transfer-Encoding: 8bit From: Will Deacon [ Upstream commit 7aed6a2c51ffc97a126e0ea0c270fab7af97ae18 ] Syzbot reports a KASAN failure early during boot on arm64 when building with GCC 12.2.0 and using the Software Tag-Based KASAN mode: | BUG: KASAN: invalid-access in smp_build_mpidr_hash arch/arm64/kernel/setup.c:133 [inline] | BUG: KASAN: invalid-access in setup_arch+0x984/0xd60 arch/arm64/kernel/setup.c:356 | Write of size 4 at addr 03ff800086867e00 by task swapper/0 | Pointer tag: [03], memory tag: [fe] Initial triage indicates that the report is a false positive and a thorough investigation of the crash by Mark Rutland revealed the root cause to be a bug in GCC: > When GCC is passed `-fsanitize=hwaddress` or > `-fsanitize=kernel-hwaddress` it ignores > `__attribute__((no_sanitize_address))`, and instruments functions > we require are not instrumented. > > [...] > > All versions [of GCC] I tried were broken, from 11.3.0 to 14.2.0 > inclusive. > > I think we have to disable KASAN_SW_TAGS with GCC until this is > fixed Disable Software Tag-Based KASAN when building with GCC by making CC_HAS_KASAN_SW_TAGS depend on !CC_IS_GCC. Cc: Andrey Konovalov Suggested-by: Mark Rutland Reported-by: syzbot+908886656a02769af987@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/000000000000f362e80620e27859@google.com Link: https://lore.kernel.org/r/ZvFGwKfoC4yVjN_X@J2N7QTR9R3 Link: https://bugzilla.kernel.org/show_bug.cgi?id=218854 Reviewed-by: Andrey Konovalov Acked-by: Mark Rutland Link: https://lore.kernel.org/r/20241014161100.18034-1-will@kernel.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- lib/Kconfig.kasan | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index ca09b1cf8ee9d..34420eb1cbfe1 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -22,8 +22,11 @@ config ARCH_DISABLE_KASAN_INLINE config CC_HAS_KASAN_GENERIC def_bool $(cc-option, -fsanitize=kernel-address) +# GCC appears to ignore no_sanitize_address when -fsanitize=kernel-hwaddress +# is passed. See https://bugzilla.kernel.org/show_bug.cgi?id=218854 (and +# the linked LKML thread) for more details. config CC_HAS_KASAN_SW_TAGS - def_bool $(cc-option, -fsanitize=kernel-hwaddress) + def_bool !CC_IS_GCC && $(cc-option, -fsanitize=kernel-hwaddress) # This option is only required for software KASAN modes. # Old GCC versions do not have proper support for no_sanitize_address. @@ -91,7 +94,7 @@ config KASAN_SW_TAGS help Enables Software Tag-Based KASAN. - Requires GCC 11+ or Clang. + Requires Clang. Supported only on arm64 CPUs and relies on Top Byte Ignore. -- 2.43.0