kasan: use stack_depot_put for Generic mode

Evict alloc/free stack traces from the stack depot for Generic KASAN once
they are evicted from the quaratine.

For auxiliary stack traces, evict the oldest stack trace once a new one is
saved (KASAN only keeps references to the last two).

Also evict all saved stack traces on krealloc.

To avoid double-evicting and mis-evicting stack traces (in case KASAN's
metadata was corrupted), reset KASAN's per-object metadata that stores
stack depot handles when the object is initialized and when it's evicted
from the quarantine.

Note that stack_depot_put is no-op if the handle is 0.

Link: https://lkml.kernel.org/r/5cef104d9b842899489b4054fe8d1339a71acee0.1700502145.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 825a0240ec02890e10a8ba67695d0d3fa3aeb211..b5d8bd26fcedbe3bf9f1d9946949642c84025f53 100644 (file)
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -50,7 +50,8 @@ depot_stack_handle_t kasan_save_stack(gfp_t flags, depot_flags_t depot_flags)
 void kasan_set_track(struct kasan_track *track, gfp_t flags)
 {
        track->pid = current->pid;
-       track->stack = kasan_save_stack(flags, STACK_DEPOT_FLAG_CAN_ALLOC);
+       track->stack = kasan_save_stack(flags,
+                       STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET);
 }
 
 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)

diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 5d168c9afb32010c3702176370e96fd4c4e7a837..50cc519e23f4f008f2a6bb38cf2179ea3a1831d1 100644 (file)
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -449,10 +449,14 @@ struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
 void kasan_init_object_meta(struct kmem_cache *cache, const void *object)
 {
        struct kasan_alloc_meta *alloc_meta;
+       struct kasan_free_meta *free_meta;
 
        alloc_meta = kasan_get_alloc_meta(cache, object);
        if (alloc_meta)
                __memset(alloc_meta, 0, sizeof(*alloc_meta));
+       free_meta = kasan_get_free_meta(cache, object);
+       if (free_meta)
+               __memset(free_meta, 0, sizeof(*free_meta));
 }
 
 size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object)
@@ -489,18 +493,20 @@ static void __kasan_record_aux_stack(void *addr, depot_flags_t depot_flags)
        if (!alloc_meta)
                return;
 
+       stack_depot_put(alloc_meta->aux_stack[1]);
        alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0];
        alloc_meta->aux_stack[0] = kasan_save_stack(0, depot_flags);
 }
 
 void kasan_record_aux_stack(void *addr)
 {
-       return __kasan_record_aux_stack(addr, STACK_DEPOT_FLAG_CAN_ALLOC);
+       return __kasan_record_aux_stack(addr,
+                       STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET);
 }
 
 void kasan_record_aux_stack_noalloc(void *addr)
 {
-       return __kasan_record_aux_stack(addr, 0);
+       return __kasan_record_aux_stack(addr, STACK_DEPOT_FLAG_GET);
 }
 
 void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
@@ -508,8 +514,16 @@ void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
        struct kasan_alloc_meta *alloc_meta;
 
        alloc_meta = kasan_get_alloc_meta(cache, object);
-       if (alloc_meta)
-               kasan_set_track(&alloc_meta->alloc_track, flags);
+       if (!alloc_meta)
+               return;
+
+       /* Evict previous stack traces (might exist for krealloc). */
+       stack_depot_put(alloc_meta->alloc_track.stack);
+       stack_depot_put(alloc_meta->aux_stack[0]);
+       stack_depot_put(alloc_meta->aux_stack[1]);
+       __memset(alloc_meta, 0, sizeof(*alloc_meta));
+
+       kasan_set_track(&alloc_meta->alloc_track, flags);
 }
 
 void kasan_save_free_info(struct kmem_cache *cache, void *object)

diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index ca4529156735920f450f4b960fe08578ace0dbae..265ca2bbe2dd83ae9189cc31a7134e02d49fe307 100644 (file)
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -143,11 +143,22 @@ static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache)
 static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
 {
        void *object = qlink_to_object(qlink, cache);
-       struct kasan_free_meta *meta = kasan_get_free_meta(cache, object);
+       struct kasan_alloc_meta *alloc_meta = kasan_get_alloc_meta(cache, object);
+       struct kasan_free_meta *free_meta = kasan_get_free_meta(cache, object);
        unsigned long flags;
 
-       if (IS_ENABLED(CONFIG_SLAB))
-               local_irq_save(flags);
+       if (alloc_meta) {
+               stack_depot_put(alloc_meta->alloc_track.stack);
+               stack_depot_put(alloc_meta->aux_stack[0]);
+               stack_depot_put(alloc_meta->aux_stack[1]);
+               __memset(alloc_meta, 0, sizeof(*alloc_meta));
+       }
+
+       if (free_meta &&
+           *(u8 *)kasan_mem_to_shadow(object) == KASAN_SLAB_FREETRACK) {
+               stack_depot_put(free_meta->free_track.stack);
+               free_meta->free_track.stack = 0;
+       }
 
        /*
         * If init_on_free is enabled and KASAN's free metadata is stored in
@@ -157,14 +168,17 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
         */
        if (slab_want_init_on_free(cache) &&
            cache->kasan_info.free_meta_offset == 0)
-               memzero_explicit(meta, sizeof(*meta));
+               memzero_explicit(free_meta, sizeof(*free_meta));
 
        /*
-        * As the object now gets freed from the quarantine, assume that its
-        * free track is no longer valid.
+        * As the object now gets freed from the quarantine,
+        * take note that its free track is no longer exists.
         */
        *(u8 *)kasan_mem_to_shadow(object) = KASAN_SLAB_FREE;
 
+       if (IS_ENABLED(CONFIG_SLAB))
+               local_irq_save(flags);
+
        ___cache_free(cache, object, _THIS_IP_);
 
        if (IS_ENABLED(CONFIG_SLAB))