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Subject[PATCH] livepatch: Cancel transition a safe way for immediate patches
Date
klp_init_transition() does not set func->transition for immediate patches.
Then klp_ftrace_handler() could use the new code immediately. As a result,
it is not safe to put the livepatch module in klp_cancel_transition().

This patch reverts most of the last minute changes klp_cancel_transition().
It keeps the warning about a misuse because it still makes sense.

Signed-off-by: Petr Mladek <pmladek@suse.com>
---
Hi,

I am afraid that Mirek was not right in the mail
https://lkml.kernel.org/r/alpine.LSU.2.20.1702161504020.16310@pobox.suse.cz
IMHO, it is not safe to put the module when the immediate
patch cannot be applied.

Best Regards,
Petr

kernel/livepatch/transition.c | 20 --------------------
1 file changed, 20 deletions(-)

diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 2de09e0c4e5c..adc0cc64aa4b 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -120,31 +120,11 @@ static void klp_complete_transition(void)
*/
void klp_cancel_transition(void)
{
- struct klp_patch *patch = klp_transition_patch;
- struct klp_object *obj;
- struct klp_func *func;
- bool immediate_func = false;
-
if (WARN_ON_ONCE(klp_target_state != KLP_PATCHED))
return;

klp_target_state = KLP_UNPATCHED;
klp_complete_transition();
-
- /*
- * In the enable error path, even immediate patches can be safely
- * removed because the transition hasn't been started yet.
- *
- * klp_complete_transition() doesn't have a module_put() for immediate
- * patches, so do it here.
- */
- klp_for_each_object(patch, obj)
- klp_for_each_func(obj, func)
- if (func->immediate)
- immediate_func = true;
-
- if (patch->immediate || immediate_func)
- module_put(patch->mod);
}

/*
--
1.8.5.6
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