Re: [PATCH 1/3] audit: cache ctx->major in audit_filter_syscall()
Paul Moore <paul(a)paul-moore.com> writes:
On Tue, Sep 27, 2022 at 6:59 PM Ankur Arora
<ankur.a.arora(a)oracle.com> wrote:
>
> ctx->major contains the current syscall number. This is, of course, a
> constant for the duration of the syscall. Unfortunately, GCC's alias
> analysis cannot prove that it is not modified via a pointer in the
> audit_filter_syscall() loop, and so always loads it from memory.
>
> ...
>
> Signed-off-by: Ankur Arora <ankur.a.arora(a)oracle.com>
> ---
> kernel/auditsc.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
This looks pretty trivial to me, but it's too late in the current -rc
cycle for this to be merged, I'll queue it up for after the upcoming
merge window closes. Thanks.
Thanks.
Ankur
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 79a5da1bc5bb..533b087c3c02 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -843,13 +843,14 @@ static void audit_filter_syscall(struct task_struct *tsk,
> {
> struct audit_entry *e;
> enum audit_state state;
> + unsigned long major = ctx->major;
>
> if (auditd_test_task(tsk))
> return;
>
> rcu_read_lock();
> list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_EXIT], list)
{
> - if (audit_in_mask(&e->rule, ctx->major) &&
> + if (audit_in_mask(&e->rule, major) &&
> audit_filter_rules(tsk, &e->rule, ctx, NULL,
> &state, false)) {
> rcu_read_unlock();
> --
> 2.31.1
--
ankur