From nobody Tue Feb 10 11:33:15 2026 Received: from mail-4316.protonmail.ch (mail-4316.protonmail.ch [185.70.43.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5A8762206B1 for ; Tue, 2 Dec 2025 14:29:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.70.43.16 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764685784; cv=none; b=lU0SEAXNZsrwFxqdPMsUvUDa6tdXq28LtLqdT+lM7OgkbLaKfpWkYjTMgM9t/1HNsvTWq2g7xs6ApRbnucLmSg3jP8Ecd7DEASqiop453EZjoIucVoFvSPgum4l2V7EXu83NQ1V2gjpKPZi7IHj6i6xCps8w5zrm8O/Z+iaXa+8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764685784; c=relaxed/simple; bh=0Ab3QKrH4PdLWaqrX5J9+3/2TCkeWIn5/xg6WydBgPU=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=aKoRJoVhEjsc1ew3TzeAAZcfxockSX7IdmmcNswjAmInERs0IgavurhgHW1JpV7DLA6ghLWqiA9MfvNqwmwpd90GV9LLG54SkLdeuDybGi/USFnrDiIwd5Py8Lv2GhMERm1wtDgGV2wrLBvxtXtPR+R7PHnjoeQ7ONWMlJf2biw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=pm.me; spf=pass smtp.mailfrom=pm.me; dkim=pass (2048-bit key) header.d=pm.me header.i=@pm.me header.b=OLO1VZQq; arc=none smtp.client-ip=185.70.43.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=pm.me Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pm.me Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=pm.me header.i=@pm.me header.b="OLO1VZQq" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pm.me; s=protonmail3; t=1764685774; x=1764944974; bh=N+YMyXrUIDlvdwT88k+hzchw//5574kLYOWxbowQd+Y=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: Feedback-ID:From:To:Cc:Date:Subject:Reply-To:Feedback-ID: Message-ID:BIMI-Selector; b=OLO1VZQqFWzj+DN9B0D2HPGIJo+ITebJMu7zH98a5j/ALNxRNFtR+KtxeEpUYnUgB 6bc8rY5Ac12NLTP29EQHiQ2xDycv7DznWVLU2LeZohPZZb5TrYqWk4JUjZEvV1DWqz TqDc444iZBFbQyKrpRqF7fd/MMr9eycaleu+XL7kgm3VG9xAxsSjSkbukfpFoUClMH HbGT1NBt1av02FxLJEUMiz8W18hTVfzVv0chKYNjWfir42/0O6H0OGaHbCpj1ALicE ziqDFswMLPEbGob8rKY+iRYfRqes/U7TFCaeUPQKkuEhihhor8zcKeNa3HG7uQZNeU 293qcGZFqQFQw== Date: Tue, 02 Dec 2025 14:29:28 +0000 To: Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Andrew Morton , Marco Elver From: Maciej Wieczor-Retman Cc: Maciej Wieczor-Retman , stable@vger.kernel.org, Maciej Wieczor-Retman , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/2] kasan: Unpoison vms[area] addresses with a common tag Message-ID: <325c5fa1043408f1afe94abab202cde9878240c5.1764685296.git.m.wieczorretman@pm.me> In-Reply-To: References: Feedback-ID: 164464600:user:proton X-Pm-Message-ID: 87d59c9c44924853cf81bc1e8bd9a2df71af726c Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Maciej Wieczor-Retman A KASAN tag mismatch, possibly causing a kernel panic, can be observed on systems with a tag-based KASAN enabled and with multiple NUMA nodes. It was reported on arm64 and reproduced on x86. It can be explained in the following points: 1. There can be more than one virtual memory chunk. 2. Chunk's base address has a tag. 3. The base address points at the first chunk and thus inherits the tag of the first chunk. 4. The subsequent chunks will be accessed with the tag from the first chunk. 5. Thus, the subsequent chunks need to have their tag set to match that of the first chunk. Use the modified __kasan_unpoison_vmalloc() to pass the tag of the first vm_struct's address when vm_structs are unpoisoned in pcpu_get_vm_areas(). Assigning a common tag resolves the pcpu chunk address mismatch. Fixes: 1d96320f8d53 ("kasan, vmalloc: add vmalloc tagging for SW_TAGS") Cc: # 6.1+ Signed-off-by: Maciej Wieczor-Retman --- Changelog v2: - Revise the whole patch to match the fixed refactorization from the first patch. Changelog v1: - Rewrite the patch message to point at the user impact of the issue. - Move helper to common.c so it can be compiled in all KASAN modes. mm/kasan/common.c | 3 ++- mm/kasan/hw_tags.c | 12 ++++++++---- mm/kasan/shadow.c | 15 +++++++++++---- 3 files changed, 21 insertions(+), 9 deletions(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 7884ea7d13f9..e5a867a5670b 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -591,11 +591,12 @@ void kasan_unpoison_vmap_areas(struct vm_struct **vms= , int nr_vms, unsigned long size; void *addr; int area; + u8 tag =3D get_tag(vms[0]->addr); =20 for (area =3D 0 ; area < nr_vms ; area++) { size =3D vms[area]->size; addr =3D vms[area]->addr; - vms[area]->addr =3D __kasan_unpoison_vmap_areas(addr, size, flags); + vms[area]->addr =3D __kasan_unpoison_vmap_areas(addr, size, flags, tag); } } #endif diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index 4b7936a2bd6f..2a02b898b9d8 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -317,7 +317,7 @@ static void init_vmalloc_pages(const void *start, unsig= ned long size) } =20 static void *__kasan_unpoison_vmalloc(const void *start, unsigned long siz= e, - kasan_vmalloc_flags_t flags) + kasan_vmalloc_flags_t flags, int unpoison_tag) { u8 tag; unsigned long redzone_start, redzone_size; @@ -361,7 +361,11 @@ static void *__kasan_unpoison_vmalloc(const void *star= t, unsigned long size, return (void *)start; } =20 - tag =3D kasan_random_tag(); + if (unpoison_tag < 0) + tag =3D kasan_random_tag(); + else + tag =3D unpoison_tag; + start =3D set_tag(start, tag); =20 /* Unpoison and initialize memory up to size. */ @@ -390,7 +394,7 @@ static void *__kasan_unpoison_vmalloc(const void *start= , unsigned long size, void *__kasan_random_unpoison_vmalloc(const void *start, unsigned long siz= e, kasan_vmalloc_flags_t flags) { - return __kasan_unpoison_vmalloc(start, size, flags); + return __kasan_unpoison_vmalloc(start, size, flags, -1); } =20 void __kasan_poison_vmalloc(const void *start, unsigned long size) @@ -405,7 +409,7 @@ void __kasan_poison_vmalloc(const void *start, unsigned= long size) void *__kasan_unpoison_vmap_areas(void *addr, unsigned long size, kasan_vmalloc_flags_t flags, u8 tag) { - return __kasan_unpoison_vmalloc(addr, size, flags); + return __kasan_unpoison_vmalloc(addr, size, flags, tag); } #endif =20 diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index 0a8d8bf6e9cf..7a66ffc1d5b3 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -625,8 +625,10 @@ void kasan_release_vmalloc(unsigned long start, unsign= ed long end, } =20 static void *__kasan_unpoison_vmalloc(const void *start, unsigned long siz= e, - kasan_vmalloc_flags_t flags) + kasan_vmalloc_flags_t flags, int unpoison_tag) { + u8 tag; + /* * Software KASAN modes unpoison both VM_ALLOC and non-VM_ALLOC * mappings, so the KASAN_VMALLOC_VM_ALLOC flag is ignored. @@ -648,7 +650,12 @@ static void *__kasan_unpoison_vmalloc(const void *star= t, unsigned long size, !(flags & KASAN_VMALLOC_PROT_NORMAL)) return (void *)start; =20 - start =3D set_tag(start, kasan_random_tag()); + if (unpoison_tag < 0) + tag =3D kasan_random_tag(); + else + tag =3D unpoison_tag; + + start =3D set_tag(start, tag); kasan_unpoison(start, size, false); return (void *)start; } @@ -656,13 +663,13 @@ static void *__kasan_unpoison_vmalloc(const void *sta= rt, unsigned long size, void *__kasan_random_unpoison_vmalloc(const void *start, unsigned long siz= e, kasan_vmalloc_flags_t flags) { - return __kasan_unpoison_vmalloc(start, size, flags); + return __kasan_unpoison_vmalloc(start, size, flags, -1); } =20 void *__kasan_unpoison_vmap_areas(void *addr, unsigned long size, kasan_vmalloc_flags_t flags, u8 tag) { - return __kasan_unpoison_vmalloc(addr, size, flags); + return __kasan_unpoison_vmalloc(addr, size, flags, tag); } =20 /* --=20 2.52.0