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Wed, 18 May 2022 05:56:20 -0700 (PDT) Received: from [192.168.1.100] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id je19-20020a170903265300b0015e8d4eb295sm1557875plb.223.2022.05.18.05.56.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 May 2022 05:56:19 -0700 (PDT) Content-Type: multipart/mixed; boundary="------------0r0puKxDv8vMP2cjpXkFteNT" Message-ID: <06710b30-fec8-b593-3af4-1318515b41d8@kernel.dk> Date: Wed, 18 May 2022 06:56:18 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [REPORT] Use-after-free Read in __fdget_raw in v5.10.y Content-Language: en-US From: Jens Axboe To: Lee Jones Cc: Pavel Begunkov , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org References: <97cba3e1-4ef7-0a17-8456-e0787d6702c6@kernel.dk> <3d271554-9ddc-07ad-3ff8-30aba31f8bf2@kernel.dk> In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org This is a multi-part message in MIME format. --------------0r0puKxDv8vMP2cjpXkFteNT Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/18/22 6:54 AM, Jens Axboe wrote: > On 5/18/22 6:52 AM, Jens Axboe wrote: >> On 5/18/22 6:50 AM, Lee Jones wrote: >>> On Tue, 17 May 2022, Jens Axboe wrote: >>> >>>> On 5/17/22 7:00 AM, Lee Jones wrote: >>>>> On Tue, 17 May 2022, Jens Axboe wrote: >>>>> >>>>>> On 5/17/22 6:36 AM, Lee Jones wrote: >>>>>>> On Tue, 17 May 2022, Jens Axboe wrote: >>>>>>> >>>>>>>> On 5/17/22 6:24 AM, Lee Jones wrote: >>>>>>>>> On Tue, 17 May 2022, Jens Axboe wrote: >>>>>>>>> >>>>>>>>>> On 5/17/22 5:41 AM, Lee Jones wrote: >>>>>>>>>>> Good afternoon Jens, Pavel, et al., >>>>>>>>>>> >>>>>>>>>>> Not sure if you are presently aware, but there appears to be a >>>>>>>>>>> use-after-free issue affecting the io_uring worker driver (fs/io-wq.c) >>>>>>>>>>> in Stable v5.10.y. >>>>>>>>>>> >>>>>>>>>>> The full sysbot report can be seen below [0]. >>>>>>>>>>> >>>>>>>>>>> The C-reproducer has been placed below that [1]. >>>>>>>>>>> >>>>>>>>>>> I had great success running this reproducer in an infinite loop. >>>>>>>>>>> >>>>>>>>>>> My colleague reverse-bisected the fixing commit to: >>>>>>>>>>> >>>>>>>>>>> commit fb3a1f6c745ccd896afadf6e2d6f073e871d38ba >>>>>>>>>>> Author: Jens Axboe >>>>>>>>>>> Date: Fri Feb 26 09:47:20 2021 -0700 >>>>>>>>>>> >>>>>>>>>>> io-wq: have manager wait for all workers to exit >>>>>>>>>>> >>>>>>>>>>> Instead of having to wait separately on workers and manager, just have >>>>>>>>>>> the manager wait on the workers. We use an atomic_t for the reference >>>>>>>>>>> here, as we need to start at 0 and allow increment from that. Since the >>>>>>>>>>> number of workers is naturally capped by the allowed nr of processes, >>>>>>>>>>> and that uses an int, there is no risk of overflow. >>>>>>>>>>> >>>>>>>>>>> Signed-off-by: Jens Axboe >>>>>>>>>>> >>>>>>>>>>> fs/io-wq.c | 30 ++++++++++++++++++++++-------- >>>>>>>>>>> 1 file changed, 22 insertions(+), 8 deletions(-) >>>>>>>>>> >>>>>>>>>> Does this fix it: >>>>>>>>>> >>>>>>>>>> commit 886d0137f104a440d9dfa1d16efc1db06c9a2c02 >>>>>>>>>> Author: Jens Axboe >>>>>>>>>> Date: Fri Mar 5 12:59:30 2021 -0700 >>>>>>>>>> >>>>>>>>>> io-wq: fix race in freeing 'wq' and worker access >>>>>>>>>> >>>>>>>>>> Looks like it didn't make it into 5.10-stable, but we can certainly >>>>>>>>>> rectify that. >>>>>>>>> >>>>>>>>> Thanks for your quick response Jens. >>>>>>>>> >>>>>>>>> This patch doesn't apply cleanly to v5.10.y. >>>>>>>> >>>>>>>> This is probably why it never made it into 5.10-stable :-/ >>>>>>> >>>>>>> Right. It doesn't apply at all unfortunately. >>>>>>> >>>>>>>>> I'll have a go at back-porting it. Please bear with me. >>>>>>>> >>>>>>>> Let me know if you into issues with that and I can help out. >>>>>>> >>>>>>> I think the dependency list is too big. >>>>>>> >>>>>>> Too much has changed that was never back-ported. >>>>>>> >>>>>>> Actually the list of patches pertaining to fs/io-wq.c alone isn't so >>>>>>> bad, I did start to back-port them all but some of the big ones have >>>>>>> fs/io_uring.c changes incorporated and that list is huge (256 patches >>>>>>> from v5.10 to the fixing patch mentioned above). >>>>>> >>>>>> The problem is that 5.12 went to the new worker setup, and this patch >>>>>> landed after that even though it also applies to the pre-native workers. >>>>>> Hence the dependency chain isn't really as long as it seems, probably >>>>>> just a few patches backporting the change references and completions. >>>>>> >>>>>> I'll take a look this afternoon. >>>>> >>>>> Thanks Jens. I really appreciate it. >>>> >>>> Can you see if this helps? Untested... >>> >>> What base does this apply against please? >>> >>> I tried Mainline and v5.10.116 and both failed. >> >> It's against 5.10.116, so that's puzzling. Let me double check I sent >> the right one... > > Looks like I sent the one from the wrong directory, sorry about that. > This one should be better: Nope, both are the right one. Maybe your mailer is mangling the patch? I'll attach it gzip'ed here in case that helps. -- Jens Axboe --------------0r0puKxDv8vMP2cjpXkFteNT Content-Type: application/gzip; name="patch.gz" Content-Disposition: attachment; filename="patch.gz" Content-Transfer-Encoding: base64 H4sICELshGIAA3BhdGNoALVV227bRhB9lr5iYiAFJZLW/VbDQZq0DwYCG3Vj9KEoFhS5tBaS uSK5jFIU/vfM7C4p0qSbh6B6EMm9zJ45M+dsJOIYfP9RKAhGcT4S0j+llyFsax99kUT8K8yi RRyultvNNBpfXs4WQTxfb7ZhEC9hMh4v5/O+7/uNKH3XdZuR3r8HfzJdeEtw6bEBHMhVVoQK hGSnFP7tQy/jcSiLRDEF+Jpf4ZBdE8qn44ErIROIZMJxpu/2AiWfRIiLTzLb84yZPW7HHrvA bHXPYXcHkSuWyIhDeCx2R/1KwRtYipzb2JTFdDH21uBOFzN86CwCJUL4IkWkUzFH8a9CObUE 9SgMzXNA8YMTy48iYUVykOGeiSx1fjql3H9HnwMDYh9nHM8OC8ds9ADfcc7viRicCmLEQxYk EVM8VzbIKfXfEebBABf3LBW8NklcDIgtimSZfCVOjV4M53aGqzFM2J8JvmVGJAeRcNhKeTC1 xoyKhKUFL3idopQjPykfaJaXG2oSd7lZe5NZjWYdJcx4oDireG1EoSAetON6CAQHqKOJf7OT wHO4BvzX3UYFMeVIBFFgF1UlqZpOJCFl3yTH9Fa5SQX5HkPv1Q7hRsyCloluMscyUda1ehKh tMDDSPi7aKzz30ajt9GFZ9KorSZwupI3f7Df7u+dOobBAMWFVfuPQnfUuFHkVn17pjXtOWYk 46rIEoiDQ67JfNaFXE1W3grc1XSO2v8f6khZGZu6voabO/bn7+yXjx8/s4fbD3cPt7/SklbN UNDIzTGTIc9znuvK+mfFV+tsUbGkwZ6z4sjslia9V9otdO4Iluvup8zX06k3wdTXU+zhulVo /JQQewqS4BHz1uYxjAIVaLwUVlNCQnGMF8hC/fw93ZeSx3r7LwtoK+dXdRrTB+q0NxoCRsWu ubsHkUPO8UZIIjhxeMTXHc+QcvzYBV+4bdMclATiBIYji4kgsC1qxpTgw81npiN6oE+nzHkJ DD2MaUmQrBwDKpbomUG4M+LQLU3DPcNTNWv7RHdkyvO/aOHfnmXT9igB8+D24dMnm295nHFa c+Az9ngLh9sJw/1xFG4XCLdpvjT7ihZPgVD69POV1qXKMuB3++Olh59vg3Mrj62L64t7MjM3 92Q+7bi6hyZxo2anSHLxmPAIJV6gLqOmhhk1edXqpF802lZepc1QQl3zL/IuBY6t22LQg3Hp yzhhBdeyZaehRzJWDy4aYxeVxb4pPfYcT3c29No+UVtyZalcbbzJhLhcbxqOqD2AMcsSViyT /7QMsXS8emDtxjabXMnji1O1tbUV94rgflxvXXLTFvpKD1e1hk5M/W8ylczZqQoAAA== --------------0r0puKxDv8vMP2cjpXkFteNT--