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[2003:cb:c739:600:d2fb:3a8a:9944:7910]) by smtp.gmail.com with ESMTPSA id a7-20020adfeec7000000b00349cadc5024sm11659985wrp.61.2024.04.22.03.38.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 22 Apr 2024 03:38:09 -0700 (PDT) Message-ID: Date: Mon, 22 Apr 2024 12:38:05 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [mm?] WARNING in __page_table_check_ptes_set From: David Hildenbrand To: syzbot , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, pasha.tatashin@soleen.com, syzkaller-bugs@googlegroups.com References: <000000000000ca4df20616a0fe16@google.com> <71cf84d4-77d2-42d7-a649-b67497b171f6@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: <71cf84d4-77d2-42d7-a649-b67497b171f6@redhat.com> X-Mimecast-Spam-Score: 1 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 82BB0A0012 X-Stat-Signature: c8fc6t988pj3mpmqesfkgormyrgnegug X-Rspam-User: X-HE-Tag: 1713782293-701720 X-HE-Meta: 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 J2Q/C75f 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 1zv3btYK sdfgAHhKfgCA2+VUmxBi77D+r7OMIcxRgk5GJSFnJWM2fskGQvylE2OpvXUoubFp X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 22.04.24 12:07, David Hildenbrand wrote: > On 21.04.24 22:16, syzbot wrote: >> Hello, >> >> syzbot found the following issue on: >> >> HEAD commit: 4eab35893071 Add linux-next specific files for 20240417 >> git tree: linux-next >> console+strace: https://syzkaller.appspot.com/x/log.txt?x=1727a61b180000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=27920e47287645ff >> dashboard link: https://syzkaller.appspot.com/bug?extid=d8426b591c36b21c750e >> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=156da22d180000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=163dfec7180000 >> >> Downloadable assets: >> disk image: https://storage.googleapis.com/syzbot-assets/9f7d6c097fb4/disk-4eab3589.raw.xz >> vmlinux: https://storage.googleapis.com/syzbot-assets/287b16352982/vmlinux-4eab3589.xz >> kernel image: https://storage.googleapis.com/syzbot-assets/23839c65c573/bzImage-4eab3589.xz >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+d8426b591c36b21c750e@syzkaller.appspotmail.com >> >> ------------[ cut here ]------------ >> WARNING: CPU: 0 PID: 5084 at mm/page_table_check.c:199 __page_table_check_pte mm/page_table_check.c:199 [inline] >> WARNING: CPU: 0 PID: 5084 at mm/page_table_check.c:199 __page_table_check_ptes_set+0x1db/0x420 > > I think this is > > if (pte_present(pte) && pte_uffd_wp(pte)) > WARN_ON_ONCE(pte_write(pte)); > > mm/page_table_check.c:213 >> Modules linked in: >> CPU: 0 PID: 5084 Comm: syz-executor382 Not tainted 6.9.0-rc4-next-20240417-syzkaller #0 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 >> RIP: 0010:__page_table_check_pte mm/page_table_check.c:199 [inline] >> RIP: 0010:__page_table_check_ptes_set+0x1db/0x420 mm/page_table_check.c:213 >> Code: 48 8b 7c 24 40 48 c7 c6 80 19 46 8e e8 ee df 8e ff 41 83 fc 1d 74 18 41 83 fc 1a 75 1d e8 5d da 8e ff eb 10 e8 56 da 8e ff 90 <0f> 0b 90 eb 10 e8 4b da 8e ff 90 0f 0b 90 eb 05 e8 40 da 8e ff 48 >> RSP: 0018:ffffc9000366f740 EFLAGS: 00010293 >> RAX: ffffffff8207833a RBX: ffffc9000366f7c0 RCX: ffff888022af3c00 >> RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000000 >> RBP: ffffc9000366f830 R08: ffffffff820782af R09: 1ffffd40000a6a10 >> R10: dffffc0000000000 R11: fffff940000a6a11 R12: 0000000000000000 >> R13: 0000000014d42c67 R14: 0000000000000001 R15: 0000000000000000 >> FS: 0000555567f79380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: 000000000066c7e0 CR3: 0000000078cb0000 CR4: 00000000003506f0 >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >> Call Trace: >> >> page_table_check_ptes_set include/linux/page_table_check.h:74 [inline] >> set_ptes include/linux/pgtable.h:267 [inline] >> __ptep_modify_prot_commit include/linux/pgtable.h:1269 [inline] >> ptep_modify_prot_commit include/linux/pgtable.h:1302 [inline] >> change_pte_range mm/mprotect.c:194 [inline] >> change_pmd_range mm/mprotect.c:424 [inline] >> change_pud_range mm/mprotect.c:457 [inline] >> change_p4d_range mm/mprotect.c:480 [inline] >> change_protection_range mm/mprotect.c:508 [inline] >> change_protection+0x2770/0x3cc0 mm/mprotect.c:542 >> mprotect_fixup+0x740/0xa90 mm/mprotect.c:655 >> do_mprotect_pkey+0x90d/0xe00 mm/mprotect.c:820 >> __do_sys_mprotect mm/mprotect.c:841 [inline] >> __se_sys_mprotect mm/mprotect.c:838 [inline] >> __x64_sys_mprotect+0x80/0x90 mm/mprotect.c:838 >> do_syscall_x64 arch/x86/entry/common.c:52 [inline] >> do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 >> entry_SYSCALL_64_after_hwframe+0x77/0x7f >> RIP: 0033:0x7f45514bf429 >> Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 >> RSP: 002b:00007ffe52191598 EFLAGS: 00000246 ORIG_RAX: 000000000000000a >> RAX: ffffffffffffffda RBX: 00007ffe52191768 RCX: 00007f45514bf429 >> RDX: 000000000000000f RSI: 0000000000004000 RDI: 0000000020ffc000 >> RBP: 00007f4551532610 R08: 00007ffe52191768 R09: 00007ffe52191768 >> R10: 00007ffe52191768 R11: 0000000000000246 R12: 0000000000000001 >> R13: 00007ffe52191758 R14: 0000000000000001 R15: 0000000000000001 >> > > Did we find a real issue that involves mprotect()? > > At least can_change_pte_writable() should always return "false" for > userfaultfd_pte_wp(). > > Do we maybe have a uffd-wp PTE outside of a UFFD_WP VMA? > > Or was the PTE already writable and we only detect it now as we call > mprotect()? (missed to detect it earlier?) Staring at the reproducer, we do syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1, /*offset=*/0ul); syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul, /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1, /*offset=*/0ul); -> Writable anonymous memmory syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1, /*offset=*/0ul); intptr_t res = 0; res = syscall(__NR_userfaultfd, /*flags=UFFD_USER_MODE_ONLY|O_NONBLOCK*/ 0x801ul); if (res != -1) r[0] = res; *(uint64_t*)0x200004c0 = 0xaa; *(uint64_t*)0x200004c8 = 0; *(uint64_t*)0x200004d0 = 0; syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0xc018aa3f, /*arg=*/0x200004c0ul); -> _UFFDIO_API handshake? syscall(__NR_mprotect, /*addr=*/0x20ffc000ul, /*len=*/0x3000ul, /*prot=PROT_SEM|PROT_EXEC*/ 0xcul); -> Protect target range R/O. I assume: no page populated yet? -> 3 pages starting at 0x20ffc000ul; *(uint64_t*)0x20000180 = 0x20ffc000; *(uint64_t*)0x20000188 = 0x3000; *(uint64_t*)0x20000190 = 3; *(uint64_t*)0x20000198 = 0; syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0xc020aa00, /*arg=*/0x20000180ul); -> _UFFDIO_REGISTER (aa00) -> _range = 3 pages starting at 0x20ffc000ul -> _mode = UFFDIO_REGISTER_MODE_WP | UFFDIO_REGISTER_MODE_MINOR *(uint64_t*)0x20000000 = 0x20ffd000; *(uint64_t*)0x20000008 = 0x20ffb000; *(uint64_t*)0x20000010 = 0x1000; *(uint64_t*)0x20000018 = 3; *(uint64_t*)0x20000020 = 0; syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0xc028aa03, /*arg=*/0x20000000ul); -> _UFFDIO_COPY (aa03) -> dst = 0x20ffd000 -> src = 0x20ffb000 -> len = 0x1000 (single page) -> mode = UFFDIO_COPY_MODE_DONTWAKE|UFFDIO_COPY_MODE_WP -> We are copying into the R/O range. src should be R/W and trigger a page fault on access where we get a fresh page. *(uint16_t*)0x200000c0 = 1; *(uint64_t*)0x200000c8 = 0x20000040; *(uint16_t*)0x20000040 = 6; *(uint8_t*)0x20000042 = 0; *(uint8_t*)0x20000043 = 0; *(uint32_t*)0x20000044 = 0x7fffffff; res = syscall(__NR_seccomp, /*op=*/1ul, /*flags=*/0ul, /*arg=*/0x200000c0ul); if (res != -1) r[1] = res; syscall(__NR_open_tree, /*dfd=*/-1, /*filename=*/0ul, /*flags=*/0ul); -> No idea what happens here and if it is relevant. If __NR_seccomp failed, we would no set r[1]. syscall(__NR_close_range, /*fd=*/r[1], /*max_fd=*/-1, /*flags=*/0ul); -> Is that closing uffd as well, especially if __NR_seccomp failed? syscall(__NR_mprotect, /*addr=*/0x20ffc000ul, /*len=*/0x4000ul, /*prot=PROT_SEM|PROT_WRITE|PROT_READ|PROT_EXEC*/ 0xful); -> Restore write permissions. This seems to fire the uffd-wp page table check I assume. -- Cheers, David / dhildenb