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Mon, 18 Jan 2021 04:27:12 -0800 (PST) Subject: Re: [PATCH] io_uring: fix NULL pointer dereference for async cancel close To: Joseph Qi , Jens Axboe Cc: io-uring@vger.kernel.org, Xiaoguang Wang References: <1610963424-27129-1-git-send-email-joseph.qi@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== Message-ID: <4f1a8b42-8440-0e9a-ca01-497ccd438b56@gmail.com> Date: Mon, 18 Jan 2021 12:23:35 +0000 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: <1610963424-27129-1-git-send-email-joseph.qi@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 18/01/2021 09:50, Joseph Qi wrote: > Abaci reported the following crash: > > [ 31.252589] BUG: kernel NULL pointer dereference, address: 00000000000000d8 > [ 31.253942] #PF: supervisor read access in kernel mode > [ 31.254945] #PF: error_code(0x0000) - not-present page > [ 31.255964] PGD 800000010b76f067 P4D 800000010b76f067 PUD 10b462067 PMD 0 > [ 31.257221] Oops: 0000 [#1] SMP PTI > [ 31.257923] CPU: 1 PID: 1788 Comm: io_uring-sq Not tainted 5.11.0-rc4 #1 > [ 31.259175] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 > [ 31.260232] RIP: 0010:__lock_acquire+0x19d/0x18c0 > [ 31.261144] Code: 00 00 8b 1d fd 56 dd 08 85 db 0f 85 43 05 00 00 48 c7 c6 98 7b 95 82 48 c7 c7 57 96 93 82 e8 9a bc f5 ff 0f 0b e9 2b 05 00 00 <48> 81 3f c0 ca 67 8a b8 00 00 00 00 41 0f 45 c0 89 04 24 e9 81 fe > [ 31.264297] RSP: 0018:ffffc90001933828 EFLAGS: 00010002 > [ 31.265320] RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000000 > [ 31.266594] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000000000d8 > [ 31.267922] RBP: 0000000000000246 R08: 0000000000000001 R09: 0000000000000000 > [ 31.269262] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > [ 31.270550] R13: 0000000000000000 R14: ffff888106e8a140 R15: 00000000000000d8 > [ 31.271760] FS: 0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000 > [ 31.273269] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 31.274330] CR2: 00000000000000d8 CR3: 0000000106efa004 CR4: 00000000003706e0 > [ 31.275613] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 31.276855] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 31.278065] Call Trace: > [ 31.278649] lock_acquire+0x31a/0x440 > [ 31.279404] ? close_fd_get_file+0x39/0x160 > [ 31.280276] ? __lock_acquire+0x647/0x18c0 > [ 31.281112] _raw_spin_lock+0x2c/0x40 > [ 31.281821] ? close_fd_get_file+0x39/0x160 > [ 31.282586] close_fd_get_file+0x39/0x160 > [ 31.283338] io_issue_sqe+0x1334/0x14e0 > [ 31.284053] ? lock_acquire+0x31a/0x440 > [ 31.284763] ? __io_free_req+0xcf/0x2e0 > [ 31.285504] ? __io_free_req+0x175/0x2e0 > [ 31.286247] ? find_held_lock+0x28/0xb0 > [ 31.286968] ? io_wq_submit_work+0x7f/0x240 > [ 31.287733] io_wq_submit_work+0x7f/0x240 > [ 31.288486] io_wq_cancel_cb+0x161/0x580 > [ 31.289230] ? io_wqe_wake_worker+0x114/0x360 > [ 31.290020] ? io_uring_get_socket+0x40/0x40 > [ 31.290832] io_async_find_and_cancel+0x3b/0x140 > [ 31.291676] io_issue_sqe+0xbe1/0x14e0 > [ 31.292405] ? __lock_acquire+0x647/0x18c0 > [ 31.293207] ? __io_queue_sqe+0x10b/0x5f0 > [ 31.293986] __io_queue_sqe+0x10b/0x5f0 > [ 31.294747] ? io_req_prep+0xdb/0x1150 > [ 31.295485] ? mark_held_locks+0x6d/0xb0 > [ 31.296252] ? mark_held_locks+0x6d/0xb0 > [ 31.297019] ? io_queue_sqe+0x235/0x4b0 > [ 31.297774] io_queue_sqe+0x235/0x4b0 > [ 31.298496] io_submit_sqes+0xd7e/0x12a0 > [ 31.299275] ? _raw_spin_unlock_irq+0x24/0x30 > [ 31.300121] ? io_sq_thread+0x3ae/0x940 > [ 31.300873] io_sq_thread+0x207/0x940 > [ 31.301606] ? do_wait_intr_irq+0xc0/0xc0 > [ 31.302396] ? __ia32_sys_io_uring_enter+0x650/0x650 > [ 31.303321] kthread+0x134/0x180 > [ 31.303982] ? kthread_create_worker_on_cpu+0x90/0x90 > [ 31.304886] ret_from_fork+0x1f/0x30 > > This is caused by NULL files when async cancel close, which has > IO_WQ_WORK_NO_CANCEL set and continue to do work. Fix it by also setting > needs_files for IORING_OP_ASYNC_CANCEL. Looks good enough for a quick late-rc fix, Reviewed-by: Pavel Begunkov But we need need to rework this NO_CANCEL case for the future. A reproducer would help much, do you have one? Or even better a liburing test? > > Reported-by: Abaci > Cc: stable@vger.kernel.org # 5.6+ > Signed-off-by: Joseph Qi > --- > fs/io_uring.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 985a9e3..8eb1349 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -883,7 +883,10 @@ struct io_op_def { > .pollin = 1, > .work_flags = IO_WQ_WORK_MM | IO_WQ_WORK_FILES, > }, > - [IORING_OP_ASYNC_CANCEL] = {}, > + [IORING_OP_ASYNC_CANCEL] = { > + /* for async cancel close */ > + .needs_file = 1, > + }, > [IORING_OP_LINK_TIMEOUT] = { > .needs_async_data = 1, > .async_size = sizeof(struct io_timeout_data), > -- Pavel Begunkov