| Message ID | 1544109187-13805-1-git-send-email-alex.popov@linux.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/1] stackleak: Register the 'stackleak_cleanup' pass before the '*free_cfg' pass | expand |
On Thu, Dec 6, 2018 at 7:13 AM Alexander Popov <alex.popov@linux.com> wrote: > > 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> Thanks! I've applied this to me tree and I'll send a pull request soon. -Kees > --- > 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 >
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"));
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(-)