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[PATCH v2 1/1] stackleak: Register the 'stackleak_cleanup' pass before the '*free_cfg' pass
- From: Alexander Popov <alex dot popov at linux dot com>
- To: kernel-hardening at lists dot openwall dot com, Kees Cook <keescook at chromium dot org>, Jann Horn <jannh at google dot com>, Andy Lutomirski <luto at kernel dot org>, Borislav Petkov <bp at alien8 dot de>, Thomas Gleixner <tglx at linutronix dot de>, Dave Hansen <dave dot hansen at linux dot intel dot com>, Steven Rostedt <rostedt at goodmis dot org>, Peter Zijlstra <peterz at infradead dot org>, Masami Hiramatsu <mhiramat at kernel dot org>, Florian Weimer <fweimer at redhat dot com>, Richard Sandiford <richard dot sandiford at arm dot com>, Segher Boessenkool <segher at kernel dot crashing dot org>, Alexander Monakov <amonakov at ispras dot ru>, Tycho Andersen <tycho at tycho dot ws>, Laura Abbott <labbott at redhat dot com>, Mark Rutland <mark dot rutland at arm dot com>, Emese Revfy <re dot emese at gmail dot com>, Thomas Garnier <thgarnie at google dot com>, Ingo Molnar <mingo at kernel dot org>, Will Deacon <will dot deacon at arm dot com>, Alexei Starovoitov <ast at kernel dot org>, Ard Biesheuvel <ard dot biesheuvel at linaro dot org>, H Peter Anvin <hpa at zytor dot com>, David S Miller <davem at davemloft dot net>, linux-arm-kernel at lists dot infradead dot org, gcc at gcc dot gnu dot org, alex dot popov at linux dot com, linux-kernel at vger dot kernel dot org
- Date: Thu, 6 Dec 2018 18:13:07 +0300
- 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@intel.com>
Signed-off-by: Alexander Popov <alex.popov@linux.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