From 2957308343fa7c621df9f342fab88cb970b8d5f3 Mon Sep 17 00:00:00 2001 From: Chengming Zhou Date: Sat, 12 Mar 2022 23:22:20 +0800 Subject: livepatch: Don't block removal of patches that are safe to unload module_put() is not called for a patch with "forced" flag. It should block the removal of the livepatch module when the code might still be in use after forced transition. klp_force_transition() currently sets "forced" flag for all patches on the list. In fact, any patch can be safely unloaded when it passed through the consistency model in KLP_UNPATCHED transition. In other words, the "forced" flag must be set only for livepatches that are being removed. In particular, set the "forced" flag: + only for klp_transition_patch when the transition to KLP_UNPATCHED state was forced. + all replaced patches when the transition to KLP_PATCHED state was forced and the patch was replacing the existing patches. Signed-off-by: Chengming Zhou Acked-by: Joe Lawrence Reviewed-by: Petr Mladek Tested-by: Petr Mladek [mbenes@suse.cz: wording improvements] Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20220312152220.88127-1-zhouchengming@bytedance.com --- kernel/livepatch/transition.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'kernel/livepatch') diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c index 5683ac0d2566..77ef45a1e0a3 100644 --- a/kernel/livepatch/transition.c +++ b/kernel/livepatch/transition.c @@ -641,6 +641,13 @@ void klp_force_transition(void) for_each_possible_cpu(cpu) klp_update_patch_state(idle_task(cpu)); - klp_for_each_patch(patch) - patch->forced = true; + /* Set forced flag for patches being removed. */ + if (klp_target_state == KLP_UNPATCHED) + klp_transition_patch->forced = true; + else if (klp_transition_patch->replace) { + klp_for_each_patch(patch) { + if (patch != klp_transition_patch) + patch->forced = true; + } + } } -- cgit v1.2.3