From 8fb2dfb228df785bbeb4d055a74402ef4b07fc25 Mon Sep 17 00:00:00 2001 From: Alexander Popov Date: Thu, 6 Dec 2018 18:13:07 +0300 Subject: [PATCH] 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 Signed-off-by: Alexander Popov Signed-off-by: Kees Cook --- 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 2f48da98b5d4..dbd37460c573 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"));