From nobody Sun Dec 14 05:54:05 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 052FAC2BB3F for ; Mon, 20 Nov 2023 17:52:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234252AbjKTRwA (ORCPT ); Mon, 20 Nov 2023 12:52:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234461AbjKTRv0 (ORCPT ); Mon, 20 Nov 2023 12:51:26 -0500 Received: from out-173.mta1.migadu.com (out-173.mta1.migadu.com [95.215.58.173]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 919A4D70 for ; Mon, 20 Nov 2023 09:50:46 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1700502644; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RvoTVlNH/9QJKGjG7ts3ES/7xJIaYyT0JIUdEPtk5OM=; b=DNgy9uYyYrfck71UIDDMmeBlP2Bik/eXdRS59wwnt2UBuC9bsjPHLcrxPmB7E98KHzUlfS OnFiyTSIdvZJFlR6bvb819vsoHa3zDRv09EFK0vHzurXdv2QeiuJeuOu21i9cfXyy/okM9 r0Wi2UF4LVMIbr0H8VW9kEyPJyGdVBE= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v4 21/22] kasan: use stack_depot_put for Generic mode Date: Mon, 20 Nov 2023 18:47:19 +0100 Message-Id: <5cef104d9b842899489b4054fe8d1339a71acee0.1700502145.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov 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. Reviewed-by: Marco Elver Signed-off-by: Andrey Konovalov --- mm/kasan/common.c | 3 ++- mm/kasan/generic.c | 22 ++++++++++++++++++---- mm/kasan/quarantine.c | 26 ++++++++++++++++++++------ 3 files changed, 40 insertions(+), 11 deletions(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 825a0240ec02..b5d8bd26fced 100644 --- 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 =3D current->pid; - track->stack =3D kasan_save_stack(flags, STACK_DEPOT_FLAG_CAN_ALLOC); + track->stack =3D kasan_save_stack(flags, + STACK_DEPOT_FLAG_CAN_ALLOC | STACK_DEPOT_FLAG_GET); } =20 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index 5d168c9afb32..50cc519e23f4 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -449,10 +449,14 @@ struct kasan_free_meta *kasan_get_free_meta(struct km= em_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; =20 alloc_meta =3D kasan_get_alloc_meta(cache, object); if (alloc_meta) __memset(alloc_meta, 0, sizeof(*alloc_meta)); + free_meta =3D kasan_get_free_meta(cache, object); + if (free_meta) + __memset(free_meta, 0, sizeof(*free_meta)); } =20 size_t kasan_metadata_size(struct kmem_cache *cache, bool in_object) @@ -489,18 +493,20 @@ static void __kasan_record_aux_stack(void *addr, depo= t_flags_t depot_flags) if (!alloc_meta) return; =20 + stack_depot_put(alloc_meta->aux_stack[1]); alloc_meta->aux_stack[1] =3D alloc_meta->aux_stack[0]; alloc_meta->aux_stack[0] =3D kasan_save_stack(0, depot_flags); } =20 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); } =20 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); } =20 void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t f= lags) @@ -508,8 +514,16 @@ void kasan_save_alloc_info(struct kmem_cache *cache, v= oid *object, gfp_t flags) struct kasan_alloc_meta *alloc_meta; =20 alloc_meta =3D 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); } =20 void kasan_save_free_info(struct kmem_cache *cache, void *object) diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c index ca4529156735..265ca2bbe2dd 100644 --- 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 =3D qlink_to_object(qlink, cache); - struct kasan_free_meta *meta =3D kasan_get_free_meta(cache, object); + struct kasan_alloc_meta *alloc_meta =3D kasan_get_alloc_meta(cache, objec= t); + struct kasan_free_meta *free_meta =3D kasan_get_free_meta(cache, object); unsigned long flags; =20 - 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) =3D=3D KASAN_SLAB_FREETRACK) { + stack_depot_put(free_meta->free_track.stack); + free_meta->free_track.stack =3D 0; + } =20 /* * 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, stru= ct kmem_cache *cache) */ if (slab_want_init_on_free(cache) && cache->kasan_info.free_meta_offset =3D=3D 0) - memzero_explicit(meta, sizeof(*meta)); + memzero_explicit(free_meta, sizeof(*free_meta)); =20 /* - * 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) =3D KASAN_SLAB_FREE; =20 + if (IS_ENABLED(CONFIG_SLAB)) + local_irq_save(flags); + ___cache_free(cache, object, _THIS_IP_); =20 if (IS_ENABLED(CONFIG_SLAB)) --=20 2.25.1