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Mon, 04 May 2020 08:41:47 -0700 (PDT) To: Xiaoguang Wang , io-uring@vger.kernel.org Cc: axboe@kernel.dk, joseph.qi@linux.alibaba.com References: <20200504135328.29396-1-xiaoguang.wang@linux.alibaba.com> 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] io_uring: handle -EFAULT properly in io_uring_setup() Message-ID: <8f6b82d4-7e52-e25a-4f05-f16e51854df1@gmail.com> Date: Mon, 4 May 2020 18:40:42 +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: <20200504135328.29396-1-xiaoguang.wang@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 04/05/2020 16:53, Xiaoguang Wang wrote: > If copy_to_user() in io_uring_setup() failed, we'll leak many kernel > resources, which could be reproduced by using mprotect to set params At least it recycles everything upon killing the process, so that's rather not notifying a user about a successfully installed fd. Good catch > to PROT_READ. To fix this issue, refactor io_uring_create() a bit to > let it return 'struct io_ring_ctx *', then when copy_to_user() failed, > we can free kernel resource properly. > > Signed-off-by: Xiaoguang Wang > --- > fs/io_uring.c | 45 ++++++++++++++++++++++++--------------------- > 1 file changed, 24 insertions(+), 21 deletions(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 0b91b0631173..a19885dee621 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -7761,7 +7761,8 @@ static int io_uring_get_fd(struct io_ring_ctx *ctx) > return ret; > } > > -static int io_uring_create(unsigned entries, struct io_uring_params *p) > +static struct io_ring_ctx *io_uring_create(unsigned entries, > + struct io_uring_params *p) > { > struct user_struct *user = NULL; > struct io_ring_ctx *ctx; > @@ -7769,10 +7770,10 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) > int ret; > > if (!entries) > - return -EINVAL; > + return ERR_PTR(-EINVAL); > if (entries > IORING_MAX_ENTRIES) { > if (!(p->flags & IORING_SETUP_CLAMP)) > - return -EINVAL; > + return ERR_PTR(-EINVAL); > entries = IORING_MAX_ENTRIES; > } > > @@ -7792,10 +7793,10 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) > * any cq vs sq ring sizing. > */ > if (p->cq_entries < p->sq_entries) > - return -EINVAL; > + return ERR_PTR(-EINVAL); > if (p->cq_entries > IORING_MAX_CQ_ENTRIES) { > if (!(p->flags & IORING_SETUP_CLAMP)) > - return -EINVAL; > + return ERR_PTR(-EINVAL); > p->cq_entries = IORING_MAX_CQ_ENTRIES; > } > p->cq_entries = roundup_pow_of_two(p->cq_entries); > @@ -7811,7 +7812,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) > ring_pages(p->sq_entries, p->cq_entries)); > if (ret) { > free_uid(user); > - return ret; > + return ERR_PTR(ret); > } > } > > @@ -7821,7 +7822,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) > io_unaccount_mem(user, ring_pages(p->sq_entries, > p->cq_entries)); > free_uid(user); > - return -ENOMEM; > + return ERR_PTR(-ENOMEM); > } > ctx->compat = in_compat_syscall(); > ctx->account_mem = account_mem; > @@ -7853,22 +7854,14 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) > p->cq_off.overflow = offsetof(struct io_rings, cq_overflow); > p->cq_off.cqes = offsetof(struct io_rings, cqes); > > - /* > - * Install ring fd as the very last thing, so we don't risk someone > - * having closed it before we finish setup > - */ > - ret = io_uring_get_fd(ctx); > - if (ret < 0) > - goto err; > - > p->features = IORING_FEAT_SINGLE_MMAP | IORING_FEAT_NODROP | > IORING_FEAT_SUBMIT_STABLE | IORING_FEAT_RW_CUR_POS | > IORING_FEAT_CUR_PERSONALITY | IORING_FEAT_FAST_POLL; > trace_io_uring_create(ret, ctx, p->sq_entries, p->cq_entries, p->flags); > - return ret; > + return ctx; > err: > io_ring_ctx_wait_and_kill(ctx); > - return ret; > + return ERR_PTR(ret); > } > > /* > @@ -7878,6 +7871,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) > */ > static long io_uring_setup(u32 entries, struct io_uring_params __user *params) > { > + struct io_ring_ctx *ctx; > struct io_uring_params p; > long ret; > int i; > @@ -7894,12 +7888,21 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params) > IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ)) > return -EINVAL; > > - ret = io_uring_create(entries, &p); > - if (ret < 0) > - return ret; > + ctx = io_uring_create(entries, &p); > + if (IS_ERR(ctx)) > + return PTR_ERR(ctx); > > - if (copy_to_user(params, &p, sizeof(p))) > + if (copy_to_user(params, &p, sizeof(p))) { > + io_ring_ctx_wait_and_kill(ctx); > return -EFAULT; > + } > + /* > + * Install ring fd as the very last thing, so we don't risk someone > + * having closed it before we finish setup > + */ > + ret = io_uring_get_fd(ctx); > + if (ret < 0) > + io_ring_ctx_wait_and_kill(ctx); > > return ret; > } > -- Pavel Begunkov