The flag post_unpatch_enabled in struct klp_callbacks is need in
the error paths. We need to call the post_unpatch callback
only when the pre_patch one was called.
We should clear the flag in klp_post_unpatch_callback() to make
sure that the callback is not called twice. It makes the API
more safe.
Note that we actually would call the callback twice in
klp_module_coming() when klp_patch_object() fails.
In this case, we explicitly call klp_post_unpatch_callback()
for the failed object. And we are going to call it once
again when reverting operations for all the patches by
reusing the klp_module_going() code. There is a patch
doing this in the queue.
There was another mistake in the error path in klp_comming_module().
It called klp_post_unpatch_callback() only when
patch != klp_transition_patch. But klp_pre_patch_callback()
was called even for this patch.
In fact, we could remove klp_post_unpatch_callback() from
the error path at all because it will be covered by
the reuse of the klp_module_going() code. But I think
that it is cleaner this way. For example, someone
might later decide to call the callback only when
obj->patched flag is set.
Finally, I used this opportunity to make klp_pre_patch_callback()
more readable.
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
---
kernel/livepatch/core.c | 4 +---
kernel/livepatch/core.h | 8 +++++---
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index cafb5a84417d..eb134479c394 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -894,9 +894,7 @@ int klp_module_coming(struct module *mod)
pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
patch->mod->name, obj->mod->name, ret);
- if (patch != klp_transition_patch)
- klp_post_unpatch_callback(obj);
-
+ klp_post_unpatch_callback(obj);
goto err;
}
diff --git a/kernel/livepatch/core.h b/kernel/livepatch/core.h
index 6fc907b54e71..cc3aa708e0b4 100644
--- a/kernel/livepatch/core.h
+++ b/kernel/livepatch/core.h
@@ -12,10 +12,10 @@ static inline bool klp_is_object_loaded(struct klp_object *obj)
static inline int klp_pre_patch_callback(struct klp_object *obj)
{
- int ret;
+ int ret = 0;
- ret = (obj->callbacks.pre_patch) ?
- (*obj->callbacks.pre_patch)(obj) : 0;
+ if (obj->callbacks.pre_patch)
+ ret = (*obj->callbacks.pre_patch)(obj);
obj->callbacks.post_unpatch_enabled = !ret;
@@ -39,6 +39,8 @@ static inline void klp_post_unpatch_callback(struct klp_object *obj)
if (obj->callbacks.post_unpatch_enabled &&
obj->callbacks.post_unpatch)
(*obj->callbacks.post_unpatch)(obj);
+
+ obj->callbacks.post_unpatch_enabled = false;
}
#endif /* _LIVEPATCH_CORE_H */
--
1.8.5.6
--
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