diff options
Diffstat (limited to 'samples/livepatch/livepatch-shadow-fix1.c')
| -rw-r--r-- | samples/livepatch/livepatch-shadow-fix1.c | 43 |
1 files changed, 32 insertions, 11 deletions
diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c index 830c55514f9f..49b13553eaae 100644 --- a/samples/livepatch/livepatch-shadow-fix1.c +++ b/samples/livepatch/livepatch-shadow-fix1.c @@ -56,6 +56,21 @@ struct dummy { unsigned long jiffies_expire; }; +/* + * The constructor makes more sense together with klp_shadow_get_or_alloc(). + * In this example, it would be safe to assign the pointer also to the shadow + * variable returned by klp_shadow_alloc(). But we wanted to show the more + * complicated use of the API. + */ +static int shadow_leak_ctor(void *obj, void *shadow_data, void *ctor_data) +{ + void **shadow_leak = shadow_data; + void *leak = ctor_data; + + *shadow_leak = leak; + return 0; +} + struct dummy *livepatch_fix1_dummy_alloc(void) { struct dummy *d; @@ -74,7 +89,8 @@ struct dummy *livepatch_fix1_dummy_alloc(void) * pointer to handle resource release. */ leak = kzalloc(sizeof(int), GFP_KERNEL); - klp_shadow_alloc(d, SV_LEAK, &leak, sizeof(leak), GFP_KERNEL); + klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL, + shadow_leak_ctor, leak); pr_info("%s: dummy @ %p, expires @ %lx\n", __func__, d, d->jiffies_expire); @@ -82,9 +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 @@ -93,15 +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); } @@ -147,7 +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)); } |