[PATCH] headers/deps: Add header dependencies to .c files: <linux/ptrace_api.h>

From: Ingo Molnar
Date: Sat Jan 08 2022 - 05:34:07 EST



* Nathan Chancellor <nathan@xxxxxxxxxx> wrote:

> 1. kernel/stackleak.c build failure:
>
> $ make -skj"$(nproc)" ARCH=x86_64 allmodconfig kernel/stackleak.o
> kernel/stackleak.c: In function ‘stackleak_erase’:
> kernel/stackleak.c:92:13: error: implicit declaration of function ‘on_thread_stack’; did you mean ‘setup_thread_stack’? [-Werror=implicit-function-declaration]

So it turns out that my build environment didn't have the stackleak code
enabled at all:

kepler:~/mingo.tip.git> make ARCH=x86_64 allmodconfig
#
# configuration written to .config
#
kepler:~/mingo.tip.git> grep -E 'STACKLEAK|GCC_PLUGIN' .config
CONFIG_HAVE_ARCH_STACKLEAK=y
CONFIG_HAVE_GCC_PLUGINS=y

... because it failed this condition:

menuconfig GCC_PLUGINS
...
depends on $(success,test -e $(shell,$(CC) -print-file-name=plugin)/include/plugin-version.h)

... because there were no plugin headers:

kepler:~/mingo.tip.git> gcc -print-file-name=plugin
/usr/lib/gcc/x86_64-linux-gnu/10/plugin

kepler:~/mingo.tip.git> ls $(gcc -print-file-name=plugin)/include/
ls: cannot access '/usr/lib/gcc/x86_64-linux-gnu/10/plugin/include/': No such file or directory

... because I needed to install the plugin-development packages for gcc-10.

After installing those I have stackleak:

kepler:~/mingo.tip.git> grep STACKLEAK .config
CONFIG_HAVE_ARCH_STACKLEAK=y
CONFIG_GCC_PLUGIN_STACKLEAK=y
CONFIG_STACKLEAK_TRACK_MIN_SIZE=100
CONFIG_STACKLEAK_METRICS=y
CONFIG_STACKLEAK_RUNTIME_DISABLE=y

and was able to reproduce your build failure. :-)

> This is fixed with the following diff although I am unsure if that is as
> minimal as it should be.
>
> diff --git a/kernel/stackleak.c b/kernel/stackleak.c
> index ce161a8e8d97..d67c5475183b 100644
> --- a/kernel/stackleak.c
> +++ b/kernel/stackleak.c
> @@ -10,8 +10,10 @@
> * reveal and blocks some uninitialized stack variable attacks.
> */
>
> +#include <asm/processor_api.h>
> #include <linux/stackleak.h>
> #include <linux/kprobes.h>
> +#include <linux/align.h>

Yeah - I used a simpler & more generic header: <linux/ptrace_api.h> - see
the patch below.

But your solution is functionally equivalent. This fix will be included in
-v2, hopefully released later today.

Thanks,

Ingo

===============>
From: Ingo Molnar <mingo@xxxxxxxxxx>
Date: Sat, 8 Jan 2022 11:29:17 +0100
Subject: [PATCH] headers/deps: Add header dependencies to .c files: <linux/ptrace_api.h>

Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/stackleak.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/kernel/stackleak.c b/kernel/stackleak.c
index ce161a8e8d97..fde49e2f209a 100644
--- a/kernel/stackleak.c
+++ b/kernel/stackleak.c
@@ -10,6 +10,7 @@
* reveal and blocks some uninitialized stack variable attacks.
*/

+#include <linux/ptrace_api.h>
#include <linux/stackleak.h>
#include <linux/kprobes.h>