From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 EFCB01624C3 for ; Tue, 13 May 2025 13:16:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747142175; cv=none; b=cOnsUHnZFhwKW4yHmy4EtcvwcPz0mHeUOBReX6DHxrIhyMxi108JQz2W1NrYHCZZsbXhMNsu179zNrgo9ABvfcq/m8LHmxk++mzzf/F4LzYBdhz+O1XwQQ4Er0dZ0bh+OU+pZdEQCXLW6MRSSbL1gPZC55pdAfSV/HxR2oiNQp0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747142175; c=relaxed/simple; bh=dc1EvFdByajZoUd7bPWEy3aTiCwvIbfqMrCdk76T0rM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aZ0cKqHuLhdFzIbuwYhIcw/YZIJUpMD7MeM+/5xIR8pjK3CT4oJTJ2Mm7uN0IZX7s2olbPh4/OPdBrm31iYeeeuTTTLe3FGF2LmmL4zg31C+qUXgbxD3885ccY0SzSOHVsS42gCAcCWBeU2nsKeFT5tGfl35IjhYq/Xe3lsZc/8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine 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=O2B9Y93W; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine 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="O2B9Y93W" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1747142172; 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=5lK2aUXXFM24jrUuqUNjXmhdY+CHae+0dmeoTkQXG4c=; b=O2B9Y93WpJWvS2pLuUNipsNPnPWMTAqLJWaG8PlG29c56RpJPcj4eoIMzMR2pgw0KsPbyW XzasRC5ErkbJc+DOsk6tORMKJVoTY7M/H9x4OP4jJD59pCGnS4dIX/SHKZSQiS0JAwAb8v Sl7MjmmCboQSRZOtU0Pm+I8cmToHPk0= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-664-JUiFmZVdNcy0rrzRxeNetg-1; Tue, 13 May 2025 09:16:11 -0400 X-MC-Unique: JUiFmZVdNcy0rrzRxeNetg-1 X-Mimecast-MFC-AGG-ID: JUiFmZVdNcy0rrzRxeNetg_1747142170 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-43efa869b0aso42297335e9.3 for ; Tue, 13 May 2025 06:16:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1747142170; x=1747746970; 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=5lK2aUXXFM24jrUuqUNjXmhdY+CHae+0dmeoTkQXG4c=; b=WfclnzcYfxWJa2iEY8ZlCA4RC7jODT8U6P4fjfAP4ieovjlDFHi0VRjU+FpgNhW2TH G4ITb+DuCd4ardnuA8s2/OoFjhGSjDBa5whcJVteNKvpSjrNfehkNmshsxeNeXSAiC77 645dxagJ7vcHA6eziW4L0GgZ6+ivR49Z4ApbfLdv5n+Y0DL5XKexlUmEHsYxcmlGmHEd 5UH7SNXGiNiKajzDuCaeNA6+Cl02fvmcA4jrhQcvqufwsQ2dBRFW43SeuZlgwTlInIqf f/UaejnDAVmSrX6Fqe7Dd9siRgl4aV1ndbWOf2KEBBRsH09iqJcdipWQf2ncnpEi9vXn 8r8Q== X-Forwarded-Encrypted: i=1; AJvYcCXkoNwd3IUo23fyjQ8WwUij484+kbSBQk6O12tUyHom3g2NElOWCrPnruz52zv1b49qKTHlZAKKviOMJwkUHWKsspI=@vger.kernel.org X-Gm-Message-State: AOJu0Yz3NZMxbDxB0GeKwRcUPOeXGpuiigfo2liWfLY75GZ/zNRyNueJ f9Xcv5fG1bZLl9zCTGJoaz8e0DWPmqV1CmuND1eLTFneXOqI094jKlkw+KPNInWtotS8fOJEzhg 6pZhKpwpblOjKFERWdkOuSokl7idx/vDiGFETER9yYAEVFtRSiI3s6zEEpmHUI7a7fGpc+Q== X-Gm-Gg: ASbGncsqjcDFWCOnC/zRFLhDCtpXn6siaJcDnO6kegw3DtL2E5N13XbCiL1VtjLanKJ Ssy3fy2Ud/flM9+VQZa0qoQIXefGkjZ9LyRroAroIQ60ab+GmIkY/CEqY8nFc6WT3i1JWDJUaAg 7y8Rsfolp/ElyUSetghyXj4emzPs+hMV+w+9oKi2p/kA666Vu0HZ4/dxcPG/akHTNkkxiun8U+W HyUwiJTKKshEfbKhrsAdOkVmuRIcLGzDwXQzrDQ37/Gm/ys9Me41FD1kA4CEK7lxlakoVOrgMfz NevTXDS68ckAsF+3eIb/fL/+Qpm+bEpol56PZX2O5zuFTqksQom2xOu/xGHyFApu55Ly/Ne5me1 leg3PbUJYXrP7/TkkqO2uRVb4uNdazR04cBUSA6Q= X-Received: by 2002:a05:600c:608c:b0:43c:e70d:450c with SMTP id 5b1f17b1804b1-442d6dbbd6cmr141286075e9.22.1747142170039; Tue, 13 May 2025 06:16:10 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGeRzfDrwIycfq9a6Yco8QlNMnfOIsdHECdmUa8WqAn0Qia0p9wrag/isuPcxnBtSVbdOdr7Q== X-Received: by 2002:a05:600c:608c:b0:43c:e70d:450c with SMTP id 5b1f17b1804b1-442d6dbbd6cmr141285665e9.22.1747142169593; Tue, 13 May 2025 06:16:09 -0700 (PDT) Received: from ?IPV6:2003:d8:2f4d:1a00:4fdf:53e2:1a36:ba34? (p200300d82f4d1a004fdf53e21a36ba34.dip0.t-ipconnect.de. [2003:d8:2f4d:1a00:4fdf:53e2:1a36:ba34]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-442d146af31sm203932935e9.17.2025.05.13.06.16.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 13 May 2025 06:16:09 -0700 (PDT) Message-ID: <60b3386e-dbb1-4fe9-bc38-d62eba4d9c50@redhat.com> Date: Tue, 13 May 2025 15:16:08 +0200 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mm-stable] uprobes: Revert ref_ctr_offset in uprobe_unregister error path To: Jiri Olsa , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Andrii Nakryiko Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org References: <20250513122125.1617722-1-jolsa@kernel.org> From: David Hildenbrand 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: <20250513122125.1617722-1-jolsa@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: taZnPCDZ4WH1gsKzehfNs9w8YBI5q5ymRFtnEYZE080_1747142170 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 13.05.25 14:21, Jiri Olsa wrote: > From: Jiri Olsa > Thanks for debugging. > There's error path that could lead to inactive uprobe: > > 1) uprobe_register succeeds - updates instruction to int3 and > changes ref_ctr from 0 to 1 > 2) uprobe_unregister fails - int3 stays in place, but ref_ctr > is changed to 0 (it's not restored to 1 in the fail path) > uprobe is leaked > 3) another uprobe_register comes and re-uses the leaked uprobe > and succeds - but int3 is already in place, so ref_ctr update > is skipped and it stays 0 - uprobe CAN NOT be triggered now > 4) uprobe_unregister fails because ref_ctr value is unexpected > > Fixing this by reverting the updated ref_ctr value back to 1 in step 2), > which is the case when uprobe_unregister fails (int3 stays in place), > but we have already updated refctr. > > The new scenario will go as follows: > > 1) uprobe_register succeeds - updates instruction to int3 and > changes ref_ctr from 0 to 1 > 2) uprobe_unregister fails - int3 stays in place and ref_ctr > is reverted to 1.. uprobe is leaked > 3) another uprobe_register comes and re-uses the leaked uprobe > and succeds - but int3 is already in place, so ref_ctr update > is skipped and it stays 1 - uprobe CAN be triggered now > 4) uprobe_unregister succeeds > > Suggested-by: Oleg Nesterov If it's in mm-stable, we should have Fixes: ... here > Signed-off-by: Jiri Olsa > --- > Please note it's based on mm-stable branch, because it has the > latest uprobe_write_opcode rewrite changes. > > kernel/events/uprobes.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 4c965ba77f9f..84ee7b590861 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -581,8 +581,8 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma, > > out: > /* Revert back reference counter if instruction update failed. */ > - if (ret < 0 && is_register && ref_ctr_updated) > - update_ref_ctr(uprobe, mm, -1); > + if (ret < 0 && ref_ctr_updated) > + update_ref_ctr(uprobe, mm, is_register ? -1 : 1); Hm, but my patch essentially did here /* Revert back reference counter if instruction update failed. */ - if (ret && is_register && ref_ctr_updated) + if (ret < 0 && is_register && ref_ctr_updated) update_ref_ctr(uprobe, mm, -1); So how come this wasn't a problem before? -- Cheers, David / dhildenb