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 54DEB748C for ; Sun, 16 Jul 2023 19:53:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A31DC433C7; Sun, 16 Jul 2023 19:53:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689537191; bh=yMDW8IhSgAO9rglIFLE4uReLKt9ufgZmD6SWgslRtCs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hdPOt1ezifu7kJN8qZBW3d/gHFfbuJeIEWNoamENKv2BzIjhuE/0cVAcBDY4AJ8d8 h8O+EnYBxc/gK7MHo4S/H1wTWtc8gM+rpLEb8uHU96uVbbHTt9djayDLd2wnSQGLUo 25O2dd+uRiyteijd+LkiAFX9aOJLduZTQgOQGui8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nathan Chancellor , Miguel Ojeda , "Peter Zijlstra (Intel)" , Nick Desaulniers , Josh Poimboeuf , Michael Ellerman Subject: [PATCH 6.4 001/800] start_kernel: Add __no_stack_protector function attribute Date: Sun, 16 Jul 2023 21:37:34 +0200 Message-ID: <20230716194949.144206741@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230716194949.099592437@linuxfoundation.org> References: <20230716194949.099592437@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: ndesaulniers@google.com commit 514ca14ed5444b911de59ed3381dfd195d99fe4b upstream. Back during the discussion of commit a9a3ed1eff36 ("x86: Fix early boot crash on gcc-10, third try") we discussed the need for a function attribute to control the omission of stack protectors on a per-function basis; at the time Clang had support for no_stack_protector but GCC did not. This was fixed in gcc-11. Now that the function attribute is available, let's start using it. Callers of boot_init_stack_canary need to use this function attribute unless they're compiled with -fno-stack-protector, otherwise the canary stored in the stack slot of the caller will differ upon the call to boot_init_stack_canary. This will lead to a call to __stack_chk_fail() then panic. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94722 Link: https://lore.kernel.org/all/20200316130414.GC12561@hirez.programming.kicks-ass.net/ Tested-by: Nathan Chancellor Acked-by: Michael Ellerman (powerpc) Acked-by: Miguel Ojeda Acked-by: Peter Zijlstra (Intel) Signed-off-by: Nick Desaulniers Link: https://lore.kernel.org/r/20230412-no_stackp-v2-1-116f9fe4bbe7@google.com Signed-off-by: Josh Poimboeuf Signed-off-by: Greg Kroah-Hartman Signed-off-by: ndesaulniers@google.com --- arch/powerpc/kernel/smp.c | 1 + include/linux/compiler_attributes.h | 12 ++++++++++++ init/main.c | 3 ++- 3 files changed, 15 insertions(+), 1 deletion(-) --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -1605,6 +1605,7 @@ static void add_cpu_to_masks(int cpu) } /* Activate a secondary processor. */ +__no_stack_protector void start_secondary(void *unused) { unsigned int cpu = raw_smp_processor_id(); --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -256,6 +256,18 @@ #define __noreturn __attribute__((__noreturn__)) /* + * Optional: only supported since GCC >= 11.1, clang >= 7.0. + * + * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fstack_005fprotector-function-attribute + * clang: https://clang.llvm.org/docs/AttributeReference.html#no-stack-protector-safebuffers + */ +#if __has_attribute(__no_stack_protector__) +# define __no_stack_protector __attribute__((__no_stack_protector__)) +#else +# define __no_stack_protector +#endif + +/* * Optional: not supported by gcc. * * clang: https://clang.llvm.org/docs/AttributeReference.html#overloadable --- a/init/main.c +++ b/init/main.c @@ -877,7 +877,8 @@ static void __init print_unknown_bootopt memblock_free(unknown_options, len); } -asmlinkage __visible void __init __no_sanitize_address __noreturn start_kernel(void) +asmlinkage __visible __init __no_sanitize_address __noreturn __no_stack_protector +void start_kernel(void) { char *command_line; char *after_dashes;