From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-43101.protonmail.ch (mail-43101.protonmail.ch [185.70.43.101]) (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 AF1E235504C for ; Wed, 17 Dec 2025 13:48:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.70.43.101 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765979334; cv=none; b=rEIAK07xgrYdvW1uoddSHBlQ8GCtroB7opMMncma/SxI6ACwaHsQhF5hs2qtjvf5qjFD+2OLv2QQskspTue7WuGAkz5xpApwwc2KN+LIq7EfRSQvBuc6VLX3MSjzePiJISN8aKE+pGDJgR+LHJWy3tUzDGL2UB3nYNRwI9lM+eE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765979334; c=relaxed/simple; bh=GRS1FsDjj0oGm/Lst9N0ifmekfYiWb/T/G2YSJoYsQk=; h=Date:To:From:Cc:Subject:Message-ID:MIME-Version:Content-Type; b=YQpXlI0kjum5a/8r0v3guqusxhHOvyBRY0T+h5kQ4mj6acfKq3cDglSsl6sz/X/pAyC9iuydmUxOpGg7Peu4WgS78fzAMaCaUL5wyNh0vY0dmcBIVq5+hoixaDbCeVrReRPEjZqyMv0V529tbmntPSL/x46VZ5ixXulyNoipEKI= 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=Q6rcfmRS; arc=none smtp.client-ip=185.70.43.101 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="Q6rcfmRS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pm.me; s=protonmail3; t=1765979329; x=1766238529; bh=0jXeP64J9NWSfjxyXFi/0TIVi8GX+FvR7ErLahIOjKs=; h=Date:To:From:Cc:Subject:Message-ID:Feedback-ID:From:To:Cc:Date: Subject:Reply-To:Feedback-ID:Message-ID:BIMI-Selector; b=Q6rcfmRSC/AIPuIGesUV+byki77OMlY2Hrk9xgcJumpzywimv5+/Sz3qmoLlrxkMf 8RVN3C2YHHl6i8hIgmMz2RviNXg0y1QD11Lb3qbFbtKz+Z9eDLJ9ErDzK8dS+xbsOP v6ujfX4VQRlMhIC45kHXlU1oQSBHfrdOsL2qvNCAkoQVXhUW6NrbAtgdSjvfBFYfkN w7Up/fqjnB7QeUtFY9UaIzIaa98698YbuoKzG/g9CXK89Kdpvwjh0SSjAgzVLy2gA+ ACr5O/q6cOojfaxeJJlkFqa7C5HmPkqsxqbUOOhdTawb03D2l9CwDt0onCZ2ArEFDh kRF+1nSgo9hWA== Date: Wed, 17 Dec 2025 13:48:44 +0000 To: akpm@linux-foundation.org, urezki@gmail.com, kees@kernel.org, elver@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, ryabinin.a.a@gmail.com, dakr@kernel.org, glider@google.com From: Maciej Wieczor-Retman Cc: linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, m.wieczorretman@pm.me Subject: [PATCH v5 0/3] kasan: vmalloc: Fixes for the percpu allocator and vrealloc Message-ID: Feedback-ID: 164464600:user:proton X-Pm-Message-ID: 23204708c692a2f57662abaccff2e44189916c62 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Patches fix two issues related to KASAN and vmalloc. The first one, a KASAN tag mismatch, possibly resulting in a kernel panic, can be observed on systems with a tag-based KASAN enabled and with multiple NUMA nodes. Initially it was only noticed on x86 [1] but later a similar issue was also reported on arm64 [2]. Specifically the problem is related to how vm_structs interact with pcpu_chunks - both when they are allocated, assigned and when pcpu_chunk addresses are derived. When vm_structs are allocated they are unpoisoned, each with a different random tag, if vmalloc support is enabled along the KASAN mode. Later when first pcpu chunk is allocated it gets its 'base_addr' field set to the first allocated vm_struct. With that it inherits that vm_struct's tag. When pcpu_chunk addresses are later derived (by pcpu_chunk_addr(), for example in pcpu_alloc_noprof()) the base_addr field is used and offsets are added to it. If the initial conditions are satisfied then some of the offsets will point into memory allocated with a different vm_struct. So while the lower bits will get accurately derived the tag bits in the top of the pointer won't match the shadow memory contents. The solution (proposed at v2 of the x86 KASAN series [3]) is to unpoison the vm_structs with the same tag when allocating them for the per cpu allocator (in pcpu_get_vm_areas()). The second one reported by syzkaller [4] is related to vrealloc and happens because of random tag generation when unpoisoning memory without allocating new pages. This breaks shadow memory tracking and needs to reuse the existing tag instead of generating a new one. At the same time an inconsistency in used flags is corrected. The series is based on 6.19-rc1. [1] https://lore.kernel.org/all/e7e04692866d02e6d3b32bb43b998e5d17092ba4.17= 38686764.git.maciej.wieczor-retman@intel.com/ [2] https://lore.kernel.org/all/aMUrW1Znp1GEj7St@MiWiFi-R3L-srv/ [3] https://lore.kernel.org/all/CAPAsAGxDRv_uFeMYu9TwhBVWHCCtkSxoWY4xmFB_vo= wMbi8raw@mail.gmail.com/ [4] https://syzkaller.appspot.com/bug?extid=3D997752115a851cb0cf36 Changes v5: - Rebased onto 6.19-rc1. Changes v4: - Added WARN_ON_ONCE() and removed pr_warn() from last patch. - Added missing cc stable to the first patch. - Fixed stray 'Changelog v1' in the patch messages. Changes v3: - Reworded the 4th and 5th paragraphs after finding the vms[] pointers were untagged. - Redo the patches by using a flag instead of a new __kasan_vmalloc_unpoison() argument. - Added Jiayuan's patch to the series. Changes v2: - Redid the patches since last version wasn't an actual refactor as the patch promised. - Also fixed multiple mistakes and retested everything. Jiayuan Chen (1): mm/kasan: Fix incorrect unpoisoning in vrealloc for KASAN Maciej Wieczor-Retman (2): kasan: Refactor pcpu kasan vmalloc unpoison kasan: Unpoison vms[area] addresses with a common tag include/linux/kasan.h | 16 ++++++++++++++++ mm/kasan/common.c | 32 ++++++++++++++++++++++++++++++++ mm/kasan/hw_tags.c | 2 +- mm/kasan/shadow.c | 4 +++- mm/vmalloc.c | 8 ++++---- 5 files changed, 56 insertions(+), 6 deletions(-) --=20 2.52.0