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Fri, 13 Mar 2020 12:41:07 -0700 (PDT) Subject: Re: [PATCH 5.6] io_uring: NULL-deref for IOSQE_{ASYNC,DRAIN} From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org References: <3fff749b19ae1c3c2d59e88462a8a5bfc9e6689f.1584127615.git.asml.silence@gmail.com> 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== Message-ID: Date: Fri, 13 Mar 2020 22:40:12 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <3fff749b19ae1c3c2d59e88462a8a5bfc9e6689f.1584127615.git.asml.silence@gmail.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="cCA3GJdAKQEr0LutJdLQgksPPGILFBrIc" 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) --cCA3GJdAKQEr0LutJdLQgksPPGILFBrIc Content-Type: multipart/mixed; boundary="D0TMx2328THvUEcSx0ZZ8Mu6TKzxxN1cu"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: Subject: Re: [PATCH 5.6] io_uring: NULL-deref for IOSQE_{ASYNC,DRAIN} References: <3fff749b19ae1c3c2d59e88462a8a5bfc9e6689f.1584127615.git.asml.silence@gmail.com> In-Reply-To: <3fff749b19ae1c3c2d59e88462a8a5bfc9e6689f.1584127615.git.asml.silence@gmail.com> --D0TMx2328THvUEcSx0ZZ8Mu6TKzxxN1cu Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 13/03/2020 22:29, Pavel Begunkov wrote: > Processing links, io_submit_sqe() prepares requests, drops sqes, and > passes them with sqe=3DNULL to io_queue_sqe(). There IOSQE_DRAIN and/or= > IOSQE_ASYNC requests will go through the same prep, which doesn't expec= t > sqe=3DNULL and fail with NULL pointer deference. >=20 > Always do full prepare including io_alloc_async_ctx() for linked > requests, and then it can skip the second preparation. BTW, linked_timeout test fails for a good reason. The test passes NULL bu= ffer to writev and expects it to -EFAULT in io_req_defer_prep(). However, io_submit_sqe() catches this case (see head of a link case), sets REQ_F_FAIL_LINK and allows it to fail with -ECANCELED in io_queue_link_he= ad(). > Signed-off-by: Pavel Begunkov > --- > fs/io_uring.c | 8 ++++++++ > 1 file changed, 8 insertions(+) >=20 > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 55afae6f0cf4..9d43efbec960 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -4813,6 +4813,9 @@ static int io_req_defer_prep(struct io_kiocb *req= , > { > ssize_t ret =3D 0; > =20 > + if (!sqe) > + return 0; > + > if (io_op_defs[req->opcode].file_table) { > ret =3D io_grab_files(req); > if (unlikely(ret)) > @@ -5655,6 +5658,11 @@ static bool io_submit_sqe(struct io_kiocb *req, = const struct io_uring_sqe *sqe, > if (sqe_flags & (IOSQE_IO_LINK|IOSQE_IO_HARDLINK)) { > req->flags |=3D REQ_F_LINK; > INIT_LIST_HEAD(&req->link_list); > + > + if (io_alloc_async_ctx(req)) { > + ret =3D -EAGAIN; > + goto err_req; > + } > ret =3D io_req_defer_prep(req, sqe); > if (ret) > req->flags |=3D REQ_F_FAIL_LINK; >=20 --=20 Pavel Begunkov --D0TMx2328THvUEcSx0ZZ8Mu6TKzxxN1cu-- --cCA3GJdAKQEr0LutJdLQgksPPGILFBrIc Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl5r4aAACgkQWt5b1Glr +6Wm+A//aKpCUcBSZcsjq2n/tBNz7BxOkTDViGlZer1feq+qPFICwUceghpDWE4S uRAm+gOGN8ud/RpQPcKVzhyOY0J+tJh4IK/Si3BHlCceh8MO1vVY+WfiKbzx8/TZ qE5ZL94qH4cWWCI/f+Rzkuf6ZbHjmkh7KNcJf9lghsb1ei/DU0aMn6KEYDa2aqwN 5z0qyLVqiXltj9sSmL6I3F3BJAC5caFOk/K9DudoX2SfmYoR9EVxpbzVjEcfbahU RSTFA8YopkZ9fa8s8wTHd1BqLfOCZC5CubUEl8n8BXlCQj8iqQYK3mZ+I/nIrT+b /JhN3FOlkOxDbKqNWanA5+x8KJAuQJN5FcdgigtI4laFKyYSPOT7YXLpuCewnEac 9SUpJu1xpOPiJbRX112RkyD0raOf7yGpwXLCUC0H6IJHbbzQf/T5oOq4OzRg1JH7 bGAVwM209pW9CUtXZkBpz182NRuxcsoMF+W/bE52zt3n43jercRRG3mt5DzyEZxP KJwEZLWIF/FQIWsr1PYC6AAgRG8e77ITYNf0moaAibhXjwYKbuTciIbLq58bnKBs HnqcEpo5uHymy3H1oLhzqK/hhafbCb1LbLf8AtpBlsCiPS4YsdI6rlZc/aeC/VF7 hAIJSsYEHkZ8UkqpN2CTdeZx3wmcOUab5dH+fXrTanoVkDfz6s4= =+VzN -----END PGP SIGNATURE----- --cCA3GJdAKQEr0LutJdLQgksPPGILFBrIc--