linux-kernel - [PATCH 1/1] stackleak: Disable ftrace for stackleak.c

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Message-Id: <1541887530-16610-1-git-send-email-alex.popov@linux.com>
Date:   Sun, 11 Nov 2018 01:05:30 +0300
From:   Alexander Popov <alex.popov@...ux.com>
To:     kernel-hardening@...ts.openwall.com,
        Kees Cook <keescook@...omium.org>,
        Jann Horn <jannh@...gle.com>, Ingo Molnar <mingo@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Joerg Roedel <joro@...tes.org>, Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>, Jan Kara <jack@...e.cz>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Masami Hiramatsu <mhiramat@...nel.org>, x86@...nel.org,
        alex.popov@...ux.com, linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] stackleak: Disable ftrace for stackleak.c

The stackleak_erase() function is called on the trampoline stack at the
end of syscall. This stack is not big enough for ftrace operations,
e.g. it can be overflowed if we enable kprobe_events for stackleak_erase().

Let's disable ftrace for stackleak.c to avoid such situations.

Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Alexander Popov <alex.popov@...ux.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
---
 kernel/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/Makefile b/kernel/Makefile
index 7343b3a..0906f6d 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_MULTIUSER) += groups.o
 ifdef CONFIG_FUNCTION_TRACER
 # Do not trace internal ftrace files
 CFLAGS_REMOVE_irq_work.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_stackleak.o = $(CC_FLAGS_FTRACE)
 endif
 
 # Prevents flicker of uninteresting __do_softirq()/__local_bh_disable_ip()
-- 
2.7.4