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 54D3278274 for ; Fri, 22 Mar 2024 21:56:15 +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=1711144577; cv=none; b=uwgVI126Rz5TycTMVYMxBxDM7WMK+bVHM7x6XIbaFnquGPam3ysxAWbUYwyqXQSClrgyGRtm0UiHwMwxClrwCNVsX/3xrIckKbgElMQKi166OyldBz5B2hzPi1l5Kj3riAIkfvBwJzluXASjSu8X1h/Owy6u2+04QAJ8fSZFVDo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711144577; c=relaxed/simple; bh=mqI5C2sstfl9phrjs83gokfY9/p+7iYAYoYf3S8etno=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=pnZSTAxiH+TPNyk5BORRZPz09IcYL8V3MIylREZ2jaHjpIfv2ZrALE4QeYxVuWolhdruOu+opMjvHIuq/ZdTQuALa2GA6dm6sTMN0n8CcH/BSS1o6bzIVd+q152aTuHwKyHICpxcMCm6vtGSO4gPPdec00DIjsv0w2M9m5KVp6k= 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=GqXTrMwM; 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="GqXTrMwM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1711144574; 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=ilDRSs0Ait/XlZwDgiIlSIqrzhhZAq2BofMKP07LLMA=; b=GqXTrMwMhif35sGRcQMpGk11xZmCMrSTIz9HLMZ3Eor3k+imtsdgP1Oe7ZVWxb3LxMs7uo QQBsy/0IRKEshSXVKraiV6oKlmgjRE2c5MT3Sd7fPkfNnsjRfFoYskCMkzj9QfS+dH9Sfo HGbCVPfl+v0cL2d6g6Iu7GzYD4uF1U0= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-45--M2UIYXVMZGXVRfx4KZwVQ-1; Fri, 22 Mar 2024 17:56:12 -0400 X-MC-Unique: -M2UIYXVMZGXVRfx4KZwVQ-1 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-33ed2f873b4so1258639f8f.2 for ; Fri, 22 Mar 2024 14:56:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1711144570; x=1711749370; h=content-transfer-encoding:in-reply-to:organization:autocrypt :references:cc:to:from:content-language:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=ilDRSs0Ait/XlZwDgiIlSIqrzhhZAq2BofMKP07LLMA=; b=DiNOhBzGkN1TPrmdI/8j/9zv4vpHiDW2sj+mk52Tgu0IK9FcII79ygnrSig54KCvwN VasqFh5eKEhKiraslfOiWAk00OqPKmPUO3cxMHLb+Kk/cvLklW2Bbqh7YBCXhAiatAx3 MWrRWpfkOBmwjLaCF8AiCRfi+3QmDpAaZt03HvqWBoqh/YdYL3GhPj/o/doCFDUiBH8G IRoEhXlvmj2OZ7db8vT2AEgZZsnykNqb0tuqCH7oki6Cslxo5RxXyjiLRN2dS/DC6xSx cvgb5b9E90xAEGxHeswX/sZpPcfk8bwkroD8apnNt3og+KXKFf9aa/3kzWMjFLnqpxdm nybQ== X-Forwarded-Encrypted: i=1; AJvYcCUoKDKJ4ngeD0N/HLj1e3UsTP0UlyF/83P5US7Ag7fBnJ1cX31hIf0R2yygsM5q5Cabxaldl1sIjUl8FK+g04ZPF5Nm1RYhmtFNSVnJ X-Gm-Message-State: AOJu0YzWAfefASBSVMFh2UYBFyGaXBPlFZEhIv9f9qW6R5y3VCD2hmhS FQP9OwpachUUrKDvtMRmA9PfilMTp2DxHO4N6xqjfbDoo8FD0RFxGpeWiG7Wd5AXxuSHtISNocb CvBTdLbZ/lKl3V065h86S97MVxqYw0EaVbbNr4RfelVtd2bD1D5QahUAEWmwqew== X-Received: by 2002:a5d:6a44:0:b0:341:b9d2:82e7 with SMTP id t4-20020a5d6a44000000b00341b9d282e7mr426756wrw.13.1711144569914; Fri, 22 Mar 2024 14:56:09 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEgLLEm/IdbO6RfLia7LH2DHDQxsP79ZB+YJJPkRpwqbWTlGm6fv6vpR0pcdvs7yiVfvJc/eg== X-Received: by 2002:a5d:6a44:0:b0:341:b9d2:82e7 with SMTP id t4-20020a5d6a44000000b00341b9d282e7mr426747wrw.13.1711144569511; Fri, 22 Mar 2024 14:56:09 -0700 (PDT) Received: from ?IPV6:2003:cb:c71b:7e00:9339:4017:7111:82d0? (p200300cbc71b7e0093394017711182d0.dip0.t-ipconnect.de. [2003:cb:c71b:7e00:9339:4017:7111:82d0]) by smtp.gmail.com with ESMTPSA id r17-20020a05600c459100b00413f25d9104sm652216wmo.40.2024.03.22.14.56.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Mar 2024 14:56:09 -0700 (PDT) Message-ID: Date: Fri, 22 Mar 2024 22:56:08 +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: BUG: unable to handle kernel paging request in fuse_copy_do Content-Language: en-US From: David Hildenbrand To: Miklos Szeredi Cc: xingwei lee , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, samsun1006219@gmail.com, syzkaller-bugs@googlegroups.com, linux-mm , Mike Rapoport References: <620f68b0-4fe0-4e3e-856a-dedb4bcdf3a7@redhat.com> <463612f2-5590-4fb3-8273-0d64c3fd3684@redhat.com> 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: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 22.03.24 22:37, David Hildenbrand wrote: > On 22.03.24 22:33, David Hildenbrand wrote: >> On 22.03.24 22:18, David Hildenbrand wrote: >>> On 22.03.24 22:13, Miklos Szeredi wrote: >>>> On Fri, 22 Mar 2024 at 22:08, David Hildenbrand wrote: >>>>> >>>>> On 22.03.24 20:46, Miklos Szeredi wrote: >>>>>> On Fri, 22 Mar 2024 at 16:41, David Hildenbrand wrote: >>>>>> >>>>>>> But at least the vmsplice() just seems to work. Which is weird, because >>>>>>> GUP-fast should not apply (page not faulted in?) >>>>>> >>>>>> But it is faulted in, and that indeed seems to be the root cause. >>>>> >>>>> secretmem mmap() won't populate the page tables. So it's not faulted in yet. >>>>> >>>>> When we GUP via vmsplice, GUP-fast should not find it in the page tables >>>>> and fallback to slow GUP. >>>>> >>>>> There, we seem to pass check_vma_flags(), trigger faultin_page() to >>>>> fault it in, and then find it via follow_page_mask(). >>>>> >>>>> ... and I wonder how we manage to skip check_vma_flags(), or otherwise >>>>> managed to GUP it. >>>>> >>>>> vmsplice() should, in theory, never succeed here. >>>>> >>>>> Weird :/ >>>>> >>>>>> Improved repro: >>>>>> >>>>>> #define _GNU_SOURCE >>>>>> >>>>>> #include >>>>>> #include >>>>>> #include >>>>>> #include >>>>>> #include >>>>>> #include >>>>>> >>>>>> int main(void) >>>>>> { >>>>>> int fd1, fd2; >>>>>> int pip[2]; >>>>>> struct iovec iov; >>>>>> char *addr; >>>>>> int ret; >>>>>> >>>>>> fd1 = syscall(__NR_memfd_secret, 0); >>>>>> addr = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd1, 0); >>>>>> ftruncate(fd1, 7); >>>>>> addr[0] = 1; /* fault in page */ >>>> >>>> Here the page is faulted in and GUP-fast will find it. It's not in >>>> the kernel page table, but it is in the user page table, which is what >>>> matter for GUP. >>> >>> Trust me, I know the GUP code very well :P >>> >>> gup_pte_range -- GUP fast -- contains: >>> >>> if (unlikely(folio_is_secretmem(folio))) { >>> gup_put_folio(folio, 1, flags); >>> goto pte_unmap; >>> } >>> >>> So we "should" be rejecting any secretmem folios and fallback to GUP slow. >>> >>> >>> ... we don't check the same in gup_huge_pmd(), but we shouldn't ever see >>> THP in secretmem code. >>> >> >> Ehm: >> >> [ 29.441405] Secretmem fault: PFN: 1096177 >> [ 29.442092] GUP-fast: PFN: 1096177 >> >> >> ... is folio_is_secretmem() broken? >> >> ... is it something "obvious" like: >> >> diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h >> index 35f3a4a8ceb1e..6996f1f53f147 100644 >> --- a/include/linux/secretmem.h >> +++ b/include/linux/secretmem.h >> @@ -16,7 +16,7 @@ static inline bool folio_is_secretmem(struct folio *folio) >> * We know that secretmem pages are not compound and LRU so we can >> * save a couple of cycles here. >> */ >> - if (folio_test_large(folio) || !folio_test_lru(folio)) >> + if (folio_test_large(folio) || folio_test_lru(folio)) >> return false; >> >> mapping = (struct address_space *) > > ... yes, that does the trick! > Proper patch (I might send out again on Monday "officially"). There are other improvements we want to do to folio_is_secretmem() in the light of folio_fast_pin_allowed(), that I wanted to do a while ago. I might send a patch for that as well now that I'm at it. From 85558a46d9f249f26bd77dd3b18d14f248464845 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 22 Mar 2024 22:45:36 +0100 Subject: [PATCH] mm/secretmem: fix GUP-fast succeeding on secretmem folios folio_is_secretmem() states that secretmem folios cannot be LRU folios: so we may only exit early if we find an LRU folio. Yet, we exit early if we find a folio that is not a secretmem folio. Consequently, folio_is_secretmem() fails to detect secretmem folios and, therefore, we can succeed in grabbing a secretmem folio during GUP-fast, crashing the kernel when we later try reading/writing to the folio, because the folio has been unmapped from the directmap. Reported-by: xingwei lee Reported-by: yue sun Debugged-by: Miklos Szeredi Fixes: 1507f51255c9 ("mm: introduce memfd_secret system call to create "secret" memory areas") Cc: Signed-off-by: David Hildenbrand --- include/linux/secretmem.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h index 35f3a4a8ceb1..6996f1f53f14 100644 --- a/include/linux/secretmem.h +++ b/include/linux/secretmem.h @@ -16,7 +16,7 @@ static inline bool folio_is_secretmem(struct folio *folio) * We know that secretmem pages are not compound and LRU so we can * save a couple of cycles here. */ - if (folio_test_large(folio) || !folio_test_lru(folio)) + if (folio_test_large(folio) || folio_test_lru(folio)) return false; mapping = (struct address_space *) -- 2.43.2 -- Cheers, David / dhildenb