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Message-Id: <1544109187-13805-1-git-send-email-alex.popov@linux.com>
Date: Thu, 6 Dec 2018 18:13:07 +0300
From: Alexander Popov <alex.popov@...ux.com>
To: kernel-hardening@...ts.openwall.com,
Kees Cook <keescook@...omium.org>,
Jann Horn <jannh@...gle.com>,
Andy Lutomirski <luto@...nel.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>,
Masami Hiramatsu <mhiramat@...nel.org>,
Florian Weimer <fweimer@...hat.com>,
Richard Sandiford <richard.sandiford@....com>,
Segher Boessenkool <segher@...nel.crashing.org>,
Alexander Monakov <amonakov@...ras.ru>,
Tycho Andersen <tycho@...ho.ws>,
Laura Abbott <labbott@...hat.com>,
Mark Rutland <mark.rutland@....com>,
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Thomas Garnier <thgarnie@...gle.com>,
Ingo Molnar <mingo@...nel.org>,
Will Deacon <will.deacon@....com>,
Alexei Starovoitov <ast@...nel.org>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
H Peter Anvin <hpa@...or.com>,
David S Miller <davem@...emloft.net>,
linux-arm-kernel@...ts.infradead.org,
gcc@....gnu.org,
alex.popov@...ux.com,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/1] stackleak: Register the 'stackleak_cleanup' pass before the '*free_cfg' pass
Currently the 'stackleak_cleanup' pass deleting a CALL insn is executed
after the 'reload' pass. That allows gcc to do some weird optimization in
function prologues and epilogues, which are generated later [1].
Let's avoid that by registering the 'stackleak_cleanup' pass before
the '*free_cfg' pass. It's the moment when the stack frame size is
already final, function prologues and epilogues are generated, and the
machine-dependent code transformations are not done.
[1] https://www.openwall.com/lists/kernel-hardening/2018/11/23/2
Reported-by: kbuild test robot <lkp@...el.com>
Signed-off-by: Alexander Popov <alex.popov@...ux.com>
---
scripts/gcc-plugins/stackleak_plugin.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c
index 2f48da9..dbd3746 100644
--- a/scripts/gcc-plugins/stackleak_plugin.c
+++ b/scripts/gcc-plugins/stackleak_plugin.c
@@ -363,10 +363,12 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
PASS_POS_INSERT_BEFORE);
/*
- * The stackleak_cleanup pass should be executed after the
- * "reload" pass, when the stack frame size is final.
+ * The stackleak_cleanup pass should be executed before the "*free_cfg"
+ * pass. It's the moment when the stack frame size is already final,
+ * function prologues and epilogues are generated, and the
+ * machine-dependent code transformations are not done.
*/
- PASS_INFO(stackleak_cleanup, "reload", 1, PASS_POS_INSERT_AFTER);
+ PASS_INFO(stackleak_cleanup, "*free_cfg", 1, PASS_POS_INSERT_BEFORE);
if (!plugin_default_version_check(version, &gcc_version)) {
error(G_("incompatible gcc/plugin versions"));
--
2.7.4
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