Messages in this thread Patch in this message | | | From | Yang Jihong <> | Subject | [PATCH 1/3] kprobes: Fixed probe nodes not correctly removed when forcibly unoptimized | Date | Wed, 15 Feb 2023 19:54:28 +0800 |
| |
When unoptimize_kprobe forcibly unoptimize the kprobe, simply queue it in the freeing_list, and do_free_cleaned_kprobes directly reclaims the kprobe if unoptimizing_list is empty (see do_unoptimize_kprobes), which may cause WARN or UAF problems.
The specific scenarios are as follows:
Thread1 arm_kprobe(p) mutex_lock(&kprobe_mutex) __arm_kprobe(kp) p = get_optimized_kprobe(p->addr) if (unlikely(_p)) unoptimize_kprobe(_p, true) // now _p is queued in freeing_list mutex_unlock(&kprobe_mutex)
Thread2 kprobe_optimizer mutex_lock(&kprobe_mutex) do_unoptimize_kprobes if (list_empty(&unoptimizing_list)) return; // here directly returned and does not process freeing_list. ... do_free_cleaned_kprobes foreach op in freeing_list: WARN_ON_ONCE(!kprobe_unused(&op->kp)) // WANR will be triggered here. free_aggr_kprobe((&op->kp) // Delete op->kp directly, if access hash // list later, UAF problem will be triggered. mutex_unlock(&kprobe_mutex)
The freeing_list needs to be processed in do_unoptimize_kprobes regardless of whether unoptimizing_list is empty.
Signed-off-by: Yang Jihong <yangjihong1@huawei.com> --- kernel/kprobes.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 1c18ecf9f98b..0730e595f4c1 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -556,10 +556,9 @@ static void do_unoptimize_kprobes(void) lockdep_assert_cpus_held(); /* Unoptimization must be done anytime */ - if (list_empty(&unoptimizing_list)) - return; + if (!list_empty(&unoptimizing_list)) + arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list); - arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list); /* Loop on 'freeing_list' for disarming */ list_for_each_entry_safe(op, tmp, &freeing_list, list) { /* Switching from detour code to origin */ -- 2.30.GIT
| |