diff options
| -rw-r--r-- | Documentation/livepatch/shadow-vars.txt | 10 | ||||
| -rw-r--r-- | include/linux/livepatch.h | 5 | ||||
| -rw-r--r-- | kernel/livepatch/shadow.c | 26 | ||||
| -rw-r--r-- | samples/livepatch/livepatch-shadow-fix1.c | 25 | ||||
| -rw-r--r-- | samples/livepatch/livepatch-shadow-fix2.c | 27 |
5 files changed, 59 insertions, 34 deletions
diff --git a/Documentation/livepatch/shadow-vars.txt b/Documentation/livepatch/shadow-vars.txt index 9c7ae191641c..ecc09a7be5dd 100644 --- a/Documentation/livepatch/shadow-vars.txt +++ b/Documentation/livepatch/shadow-vars.txt @@ -65,11 +65,15 @@ to do actions that can be done only once when a new variable is allocated. * klp_shadow_free() - detach and free a <obj, id> shadow variable - find and remove a <obj, id> reference from global hashtable - - if found, free shadow variable + - if found + - call destructor function if defined + - free shadow variable * klp_shadow_free_all() - detach and free all <*, id> shadow variables - find and remove any <*, id> references from global hashtable - - if found, free shadow variable + - if found + - call destructor function if defined + - free shadow variable 2. Use cases @@ -136,7 +140,7 @@ variable: void sta_info_free(struct ieee80211_local *local, struct sta_info *sta) { - klp_shadow_free(sta, PS_LOCK); + klp_shadow_free(sta, PS_LOCK, NULL); kfree(sta); ... diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h index 7e084321b146..aec44b1d9582 100644 --- a/include/linux/livepatch.h +++ b/include/linux/livepatch.h @@ -189,6 +189,7 @@ static inline bool klp_have_reliable_stack(void) typedef int (*klp_shadow_ctor_t)(void *obj, void *shadow_data, void *ctor_data); +typedef void (*klp_shadow_dtor_t)(void *obj, void *shadow_data); void *klp_shadow_get(void *obj, unsigned long id); void *klp_shadow_alloc(void *obj, unsigned long id, @@ -197,8 +198,8 @@ void *klp_shadow_alloc(void *obj, unsigned long id, void *klp_shadow_get_or_alloc(void *obj, unsigned long id, size_t size, gfp_t gfp_flags, klp_shadow_ctor_t ctor, void *ctor_data); -void klp_shadow_free(void *obj, unsigned long id); -void klp_shadow_free_all(unsigned long id); +void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor); +void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor); #else /* !CONFIG_LIVEPATCH */ diff --git a/kernel/livepatch/shadow.c b/kernel/livepatch/shadow.c index b10a0bbb7f84..83958c814439 100644 --- a/kernel/livepatch/shadow.c +++ b/kernel/livepatch/shadow.c @@ -243,15 +243,26 @@ void *klp_shadow_get_or_alloc(void *obj, unsigned long id, } EXPORT_SYMBOL_GPL(klp_shadow_get_or_alloc); +static void klp_shadow_free_struct(struct klp_shadow *shadow, + klp_shadow_dtor_t dtor) +{ + hash_del_rcu(&shadow->node); + if (dtor) + dtor(shadow->obj, shadow->data); + kfree_rcu(shadow, rcu_head); +} + /** * klp_shadow_free() - detach and free a <obj, id> shadow variable * @obj: pointer to parent object * @id: data identifier + * @dtor: custom callback that can be used to unregister the variable + * and/or free data that the shadow variable points to (optional) * * This function releases the memory for this <obj, id> shadow variable * instance, callers should stop referencing it accordingly. */ -void klp_shadow_free(void *obj, unsigned long id) +void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor) { struct klp_shadow *shadow; unsigned long flags; @@ -263,8 +274,7 @@ void klp_shadow_free(void *obj, unsigned long id) (unsigned long)obj) { if (klp_shadow_match(shadow, obj, id)) { - hash_del_rcu(&shadow->node); - kfree_rcu(shadow, rcu_head); + klp_shadow_free_struct(shadow, dtor); break; } } @@ -276,11 +286,13 @@ EXPORT_SYMBOL_GPL(klp_shadow_free); /** * klp_shadow_free_all() - detach and free all <*, id> shadow variables * @id: data identifier + * @dtor: custom callback that can be used to unregister the variable + * and/or free data that the shadow variable points to (optional) * * This function releases the memory for all <*, id> shadow variable * instances, callers should stop referencing them accordingly. */ -void klp_shadow_free_all(unsigned long id) +void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor) { struct klp_shadow *shadow; unsigned long flags; @@ -290,10 +302,8 @@ void klp_shadow_free_all(unsigned long id) /* Delete all <*, id> from hash */ hash_for_each(klp_shadow_hash, i, shadow, node) { - if (klp_shadow_match(shadow, shadow->obj, id)) { - hash_del_rcu(&shadow->node); - kfree_rcu(shadow, rcu_head); - } + if (klp_shadow_match(shadow, shadow->obj, id)) + klp_shadow_free_struct(shadow, dtor); } spin_unlock_irqrestore(&klp_shadow_lock, flags); diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c index 04151c7f2631..49b13553eaae 100644 --- a/samples/livepatch/livepatch-shadow-fix1.c +++ b/samples/livepatch/livepatch-shadow-fix1.c @@ -98,9 +98,19 @@ struct dummy *livepatch_fix1_dummy_alloc(void) return d; } +static void livepatch_fix1_dummy_leak_dtor(void *obj, void *shadow_data) +{ + void *d = obj; + void **shadow_leak = shadow_data; + + kfree(*shadow_leak); + pr_info("%s: dummy @ %p, prevented leak @ %p\n", + __func__, d, *shadow_leak); +} + void livepatch_fix1_dummy_free(struct dummy *d) { - void **shadow_leak, *leak; + void **shadow_leak; /* * Patch: fetch the saved SV_LEAK shadow variable, detach and @@ -109,15 +119,10 @@ void livepatch_fix1_dummy_free(struct dummy *d) * was loaded.) */ shadow_leak = klp_shadow_get(d, SV_LEAK); - if (shadow_leak) { - leak = *shadow_leak; - klp_shadow_free(d, SV_LEAK); - kfree(leak); - pr_info("%s: dummy @ %p, prevented leak @ %p\n", - __func__, d, leak); - } else { + if (shadow_leak) + klp_shadow_free(d, SV_LEAK, livepatch_fix1_dummy_leak_dtor); + else pr_info("%s: dummy @ %p leaked!\n", __func__, d); - } kfree(d); } @@ -163,7 +168,7 @@ static int livepatch_shadow_fix1_init(void) static void livepatch_shadow_fix1_exit(void) { /* Cleanup any existing SV_LEAK shadow variables */ - klp_shadow_free_all(SV_LEAK); + klp_shadow_free_all(SV_LEAK, livepatch_fix1_dummy_leak_dtor); WARN_ON(klp_unregister_patch(&patch)); } diff --git a/samples/livepatch/livepatch-shadow-fix2.c b/samples/livepatch/livepatch-shadow-fix2.c index d6c62844dc15..b34c7bf83356 100644 --- a/samples/livepatch/livepatch-shadow-fix2.c +++ b/samples/livepatch/livepatch-shadow-fix2.c @@ -68,22 +68,27 @@ bool livepatch_fix2_dummy_check(struct dummy *d, unsigned long jiffies) return time_after(jiffies, d->jiffies_expire); } +static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data) +{ + void *d = obj; + void **shadow_leak = shadow_data; + + kfree(*shadow_leak); + pr_info("%s: dummy @ %p, prevented leak @ %p\n", + __func__, d, *shadow_leak); +} + void livepatch_fix2_dummy_free(struct dummy *d) { - void **shadow_leak, *leak; + void **shadow_leak; int *shadow_count; /* Patch: copy the memory leak patch from the fix1 module. */ shadow_leak = klp_shadow_get(d, SV_LEAK); - if (shadow_leak) { - leak = *shadow_leak; - klp_shadow_free(d, SV_LEAK); - kfree(leak); - pr_info("%s: dummy @ %p, prevented leak @ %p\n", - __func__, d, leak); - } else { + if (shadow_leak) + klp_shadow_free(d, SV_LEAK, livepatch_fix2_dummy_leak_dtor); + else pr_info("%s: dummy @ %p leaked!\n", __func__, d); - } /* * Patch: fetch the SV_COUNTER shadow variable and display @@ -93,7 +98,7 @@ void livepatch_fix2_dummy_free(struct dummy *d) if (shadow_count) { pr_info("%s: dummy @ %p, check counter = %d\n", __func__, d, *shadow_count); - klp_shadow_free(d, SV_COUNTER); + klp_shadow_free(d, SV_COUNTER, NULL); } kfree(d); @@ -140,7 +145,7 @@ static int livepatch_shadow_fix2_init(void) static void livepatch_shadow_fix2_exit(void) { /* Cleanup any existing SV_COUNTER shadow variables */ - klp_shadow_free_all(SV_COUNTER); + klp_shadow_free_all(SV_COUNTER, NULL); WARN_ON(klp_unregister_patch(&patch)); } |