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Sun, 24 Nov 2019 09:52:31 -0800 (PST) Received: from [192.168.43.199] ([109.126.143.74]) by smtp.gmail.com with ESMTPSA id s17sm5711872wmh.41.2019.11.24.09.52.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 24 Nov 2019 09:52:30 -0800 (PST) To: Jens Axboe , io-uring@vger.kernel.org References: <620023b272fef0fd76d0f91ff1876fa64864caa6.1574585281.git.asml.silence@gmail.com> <6a2fcf67-1267-a02a-98ce-435bbb2ca9bb@kernel.dk> From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Subject: Re: [PATCH v2] io_uring: fix dead-hung for non-iter fixed rw Message-ID: Date: Sun, 24 Nov 2019 20:52:03 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <6a2fcf67-1267-a02a-98ce-435bbb2ca9bb@kernel.dk> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="gbm9a60AHPgzJc3wB6cmlHGZOVL603Qaf" Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --gbm9a60AHPgzJc3wB6cmlHGZOVL603Qaf Content-Type: multipart/mixed; boundary="gpM5RufoIE47vKZ73kib1pAEiwpOsDDMl"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org Message-ID: Subject: Re: [PATCH v2] io_uring: fix dead-hung for non-iter fixed rw References: <620023b272fef0fd76d0f91ff1876fa64864caa6.1574585281.git.asml.silence@gmail.com> <6a2fcf67-1267-a02a-98ce-435bbb2ca9bb@kernel.dk> In-Reply-To: <6a2fcf67-1267-a02a-98ce-435bbb2ca9bb@kernel.dk> --gpM5RufoIE47vKZ73kib1pAEiwpOsDDMl Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 24/11/2019 20:10, Jens Axboe wrote: > On 11/24/19 1:58 AM, Pavel Begunkov wrote: >> Read/write requests to devices without implemented read/write_iter >> using fixed buffers causes general protection fault, which totally >> hangs a machine. >> >> io_import_fixed() initialises iov_iter with bvec, but loop_rw_iter() >> accesses it as iovec, so dereferencing random address. >> >> kmap() page by page in this case >=20 > This looks good to me, much cleaner/simpler. I've added a few pipe fixe= d > buffer tests to liburing as well. Didn't crash for me, but obvious > garbage coming out. I've flagged this for stable as well. >=20 The problem I have is that __user pointer is meant to be checked for not being a kernel address. I suspect, it could fail in some device, which double checks the pointer after vfs (e.g. using access_ok()= ). Am I wrong? Not a fault at least... #define access_ok(...) __range_not_ok(addr, user_addr_max()); BTW, is there anybody testing it for non x86-64 arch? --=20 Pavel Begunkov --gpM5RufoIE47vKZ73kib1pAEiwpOsDDMl-- --gbm9a60AHPgzJc3wB6cmlHGZOVL603Qaf Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl3aw0sACgkQWt5b1Glr +6Uqig//U/VRr7SUs8cCRke42cbGdZ5iZUeWX8mkdSucQq3x8mw70kw4axXtIgMb JaQc+Jj7HEa8aP/LVriTUkPuAl4I7uJPsRZk4BgL38jpAfYjFaPvlOZZP2hZGXMM igW9K9ixPqDiu9qwZ/wU/cNR5ZeTj1kL3iOSQpCMjSJb0bJ3kzy4ew/ABSKSLHQ/ OPobq1ymjw6R7zO9lwjyWjDQ54KC1q3UVuoWvM+dN3nR1d4MK/hhFYeabkSA9acW +jNgT1PIdmf7L5qZhmNm/KEKpddtWaq8/8liG1kR0aTxKU/a9L/E0Ld3j4gpE+Ge Dt9VqcaGEQJN277a8ZVjgcOjjwkcJSvCToR+ivlDcwZpn/2yWPQfdcWi8MgIhxep 0LU6GkNDWiS+7yl3A92AY4jLtrpPdBSiFPtEhzwGXJ9EbFw1iPPdKEJdCv6Np34l IpqYURjbEDmR1h9qGyZk1nmP2TlCOlGnZvEvqytYQQwqInims9htQk1KE1A53zJL Hju0EqSkVKzckN0x+YizrUNpv9j78mz/sf0/V0aXtIGTyVgmyOftYNR2kbP5R8GR bkDWeUzkujeLZVOWiFn5Nalp/E0xvKF7+J7MgkJJYb81bhG5ZcGKz5bW5SsCrpMh 6VagwShJd+15J3VuWnWr/nXdPH2dGCMNCI9RccwfW4Kf3cHWnfM= =wPe/ -----END PGP SIGNATURE----- --gbm9a60AHPgzJc3wB6cmlHGZOVL603Qaf--