From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 6C289221550 for ; Fri, 14 Feb 2025 08:12:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739520723; cv=none; b=PQXznUJ8eXeXz+F0q4jvM3II6F6E7z6WGEz7npMdhP0QXer0rf4n9JgtRxqF0U0tWBHopYbd6zpzri59AGUsRu0rHXmmLHsfm5pE0DOa4DgS/KWSeb+qq+O0U2rBBwtSKuooDd6qLnT/67O6kW3fdfqwoOi2TDn6fHHYiccB+9Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739520723; c=relaxed/simple; bh=c83toEbUGxDGViChrV/KOK7NpsU/xF5jHNNacafC6ME=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QYDPRglLDKs8KcAno3J+DjX7g+ugMdyl3WLyFYZG3XhJqELtSOW+Ugph5fA6f1QHUp6XBMiQsuCRIZAi8Di9sUTnV7hitAeBhtfNXiRK81X0gBXXT16hsuXmEzF/nP+X5TrnfdKnlYTf5vYsi6YQK+dexECMqkQT1Sd5zTCeUhg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=daD9jhNL; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="daD9jhNL" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739520720; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=svkKqK/BHsrJwB4zl/6h7GqUXx+TvbrSqp2ylJbweyw=; b=daD9jhNLTMtR+LSGGpCyVYh4gfMuzzvnEOomo7jEx5FMm19L3vlBV4PEOXmkCxabQs7SZS 988Sp+g+5Ias0y8faRjF6cF2hS4iHAHVMWkKkJ1S8Ayc1nmZKRvS0qKjteiXZ7/9gMoUys Tg7chC9kN4yQU1d4w2cO0DCRlueFkZc= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-515-NsLKR8bCPxmbWZnvbQOHAw-1; Fri, 14 Feb 2025 03:11:59 -0500 X-MC-Unique: NsLKR8bCPxmbWZnvbQOHAw-1 X-Mimecast-MFC-AGG-ID: NsLKR8bCPxmbWZnvbQOHAw Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-4394b2c19ccso14534175e9.1 for ; Fri, 14 Feb 2025 00:11:58 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1739520718; x=1740125518; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=svkKqK/BHsrJwB4zl/6h7GqUXx+TvbrSqp2ylJbweyw=; b=YqjKCtZR+cuWiEazR5yZYC2JHYyqjlZJFMIAOqynO2/JZOVqEjaD1KQ5UKmngNQRKK LzmvFS3FvgThIE6tclrPh2kZjovQmGsy0IyuoP1Fo2TshXvoVbIhB8aQw2VjJjY237Gd bK0ocVWHZCeCU+xYFJt4Vqck8AF60ASJLTPoaKTsqeWAtI6mGelKoVgR+psdxMvACqGt YlCr/sPxQNHsdwoOl16DwYGq4z0rCluCg5LjdVEAHZKUY3sOq1qgkIVAhtP/7n6O083i bBBd73RmE6exhGzuYoGqnoJVF+0jHvIVrBkDOU71f61b2eEWEH3VtBqDuHcvjNBZFhj3 0apw== X-Forwarded-Encrypted: i=1; AJvYcCXJ+wVl4fNiuOjTpKcVeGZpZgyWm9oRZBcEGsV3scBk1f07FAd0M7gA1y1Jz40N62C2R6TiFvwX62cFiO8=@vger.kernel.org X-Gm-Message-State: AOJu0YzjsWywyr7CJjbdrPUjGAV2dyUHW2QWHc8JiDg0ApPke+GOdpiW QIRVEYtcipMr8LHpJwM4SiBi+cxnT0OA6ehGtKfC7I0RqJuHF50xIFkkyqF2I5YkoPhigQgySbK LznohzitMymxdGPbyhsCnu+bZSldm420VPP2nnPUFBsi2qt9sF3RxxOFYF2yE9w== X-Gm-Gg: ASbGncvFmKasHvq1JXYolPq+82eXAhi/DeRuKZ9XneskJ2x6zzTOJ79pUZ6z6kxLXZ9 sstNM6EZgdE9BFAbABVMxkL/QEqhP+iyTZF0xsT9TtC6poqlCedgkdY8kt+k0fS5jT7t2ZcA8aK 8MBNVJWt3748SGAXB8j88i51qvcHZoA+eIXL3Tq8pwzpGhD3GAhK0wQGk7aeK/VW1F814eySTEO wC2ie9YUbCONn4dviw7F5WRmH9mDUD0sBnnaWofpyJ8P49n7e2on6PM4SsI8ULpZXDiqmH6LVYE ncBShzpnUHX3kV1oVsdyS7ueJ90ltlb4Yg== X-Received: by 2002:a05:600c:458e:b0:434:f4fa:83c4 with SMTP id 5b1f17b1804b1-439601c530amr92220535e9.29.1739520717750; Fri, 14 Feb 2025 00:11:57 -0800 (PST) X-Google-Smtp-Source: AGHT+IESIpdDMkIV9XZI+zXprC/FkLET0tfjCaeqJLBbz1eYNn1sr4KvPCg+3sfMHk/W96V5Bys/FA== X-Received: by 2002:a05:600c:458e:b0:434:f4fa:83c4 with SMTP id 5b1f17b1804b1-439601c530amr92220115e9.29.1739520717289; Fri, 14 Feb 2025 00:11:57 -0800 (PST) Received: from [192.168.3.141] (p4ff23654.dip0.t-ipconnect.de. [79.242.54.84]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38f25915146sm4010991f8f.56.2025.02.14.00.11.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 14 Feb 2025 00:11:56 -0800 (PST) Message-ID: Date: Fri, 14 Feb 2025 09:11:54 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] arm: pgtable: fix NULL pointer dereference issue To: Qi Zheng , linux@armlinux.org.uk, ezra@easyb.ch, hughd@google.com, ryan.roberts@arm.com, akpm@linux-foundation.org, muchun.song@linux.dev Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ezra Buehler , stable@vger.kernel.org References: <20250214030349.45524-1-zhengqi.arch@bytedance.com> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20250214030349.45524-1-zhengqi.arch@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 14.02.25 04:03, Qi Zheng wrote: > When update_mmu_cache_range() is called by update_mmu_cache(), the vmf > parameter is NULL, which will cause a NULL pointer dereference issue in > adjust_pte(): > > Unable to handle kernel NULL pointer dereference at virtual address 00000030 when read > Hardware name: Atmel AT91SAM9 > PC is at update_mmu_cache_range+0x1e0/0x278 > LR is at pte_offset_map_rw_nolock+0x18/0x2c > Call trace: > update_mmu_cache_range from remove_migration_pte+0x29c/0x2ec > remove_migration_pte from rmap_walk_file+0xcc/0x130 > rmap_walk_file from remove_migration_ptes+0x90/0xa4 > remove_migration_ptes from migrate_pages_batch+0x6d4/0x858 > migrate_pages_batch from migrate_pages+0x188/0x488 > migrate_pages from compact_zone+0x56c/0x954 > compact_zone from compact_node+0x90/0xf0 > compact_node from kcompactd+0x1d4/0x204 > kcompactd from kthread+0x120/0x12c > kthread from ret_from_fork+0x14/0x38 > Exception stack(0xc0d8bfb0 to 0xc0d8bff8) > > To fix it, do not rely on whether 'ptl' is equal to decide whether to hold > the pte lock, but decide it by whether CONFIG_SPLIT_PTE_PTLOCKS is > enabled. In addition, if two vmas map to the same PTE page, there is no > need to hold the pte lock again, otherwise a deadlock will occur. Just add > the need_lock parameter to let adjust_pte() know this information. > > Reported-by: Ezra Buehler > Closes: https://lore.kernel.org/lkml/CAM1KZSmZ2T_riHvay+7cKEFxoPgeVpHkVFTzVVEQ1BO0cLkHEQ@mail.gmail.com/ > Fixes: fc9c45b71f43 ("arm: adjust_pte() use pte_offset_map_rw_nolock()") > Cc: stable@vger.kernel.org > Signed-off-by: Qi Zheng > --- > Changes in v2: > - change Ezra's email address (Ezra Buehler) > - some cleanups (David Hildenbrand) > > arch/arm/mm/fault-armv.c | 38 ++++++++++++++++++++++++++------------ > 1 file changed, 26 insertions(+), 12 deletions(-) > > diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c > index 2bec87c3327d2..ea4c4e15f0d31 100644 > --- a/arch/arm/mm/fault-armv.c > +++ b/arch/arm/mm/fault-armv.c > @@ -62,7 +62,7 @@ static int do_adjust_pte(struct vm_area_struct *vma, unsigned long address, > } > > static int adjust_pte(struct vm_area_struct *vma, unsigned long address, > - unsigned long pfn, struct vm_fault *vmf) > + unsigned long pfn, bool need_lock) > { > spinlock_t *ptl; > pgd_t *pgd; > @@ -99,12 +99,11 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address, > if (!pte) > return 0; > > - /* > - * If we are using split PTE locks, then we need to take the page > - * lock here. Otherwise we are using shared mm->page_table_lock > - * which is already locked, thus cannot take it. > - */ > - if (ptl != vmf->ptl) { > + if (need_lock) { > + /* > + * Use nested version here to indicate that we are already > + * holding one similar spinlock. > + */ > spin_lock_nested(ptl, SINGLE_DEPTH_NESTING); > if (unlikely(!pmd_same(pmdval, pmdp_get_lockless(pmd)))) { > pte_unmap_unlock(pte, ptl); > @@ -114,7 +113,7 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address, > > ret = do_adjust_pte(vma, address, pfn, pte); > > - if (ptl != vmf->ptl) > + if (need_lock) > spin_unlock(ptl); > pte_unmap(pte); > > @@ -123,16 +122,18 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address, > > static void > make_coherent(struct address_space *mapping, struct vm_area_struct *vma, > - unsigned long addr, pte_t *ptep, unsigned long pfn, > - struct vm_fault *vmf) > + unsigned long addr, pte_t *ptep, unsigned long pfn) > { > struct mm_struct *mm = vma->vm_mm; > struct vm_area_struct *mpnt; > unsigned long offset; > + unsigned long pmd_start_addr, pmd_end_addr; Nit: reverse christmas tree would make us put this line at the very top. Maybe do the initialization directly: const unsigned long pmd_start_addr = ALIGN_DOWN(addr, PMD_SIZE); const unsigned long pmd_end_addr = pmd_start_addr + PMD_SIZE; > pgoff_t pgoff; > int aliases = 0; > > pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT); > + pmd_start_addr = ALIGN_DOWN(addr, PMD_SIZE); > + pmd_end_addr = pmd_start_addr + PMD_SIZE; > > /* > * If we have any shared mappings that are in the same mm > @@ -141,6 +142,14 @@ make_coherent(struct address_space *mapping, struct vm_area_struct *vma, > */ > flush_dcache_mmap_lock(mapping); > vma_interval_tree_foreach(mpnt, &mapping->i_mmap, pgoff, pgoff) { > + /* > + * If we are using split PTE locks, then we need to take the pte > + * lock. Otherwise we are using shared mm->page_table_lock which > + * is already locked, thus cannot take it. > + */ > + bool need_lock = IS_ENABLED(CONFIG_SPLIT_PTE_PTLOCKS); > + unsigned long mpnt_addr; > + > /* > * If this VMA is not in our MM, we can ignore it. > * Note that we intentionally mask out the VMA > @@ -151,7 +160,12 @@ make_coherent(struct address_space *mapping, struct vm_area_struct *vma, > if (!(mpnt->vm_flags & VM_MAYSHARE)) > continue; > offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT; > - aliases += adjust_pte(mpnt, mpnt->vm_start + offset, pfn, vmf); > + mpnt_addr = mpnt->vm_start + offset; > + > + /* Avoid deadlocks by not grabbing the same PTE lock again. */ > + if (mpnt_addr >= pmd_start_addr && mpnt_addr < pmd_end_addr) > + need_lock = false; > + aliases += adjust_pte(mpnt, mpnt_addr, pfn, need_lock); > } > flush_dcache_mmap_unlock(mapping); > if (aliases) > @@ -194,7 +208,7 @@ void update_mmu_cache_range(struct vm_fault *vmf, struct vm_area_struct *vma, > __flush_dcache_folio(mapping, folio); > if (mapping) { > if (cache_is_vivt()) > - make_coherent(mapping, vma, addr, ptep, pfn, vmf); > + make_coherent(mapping, vma, addr, ptep, pfn); > else if (vma->vm_flags & VM_EXEC) > __flush_icache_all(); > } Apart from that LGTM. Hoping it will work :) Acked-by: David Hildenbrand -- Cheers, David / dhildenb