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Sun, 06 Dec 2020 05:34:27 -0800 (PST) Subject: Re: memory leak in prepare_creds To: Hillf Danton , syzbot Cc: axboe@kernel.dk, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com References: <000000000000ca5cfb05ade37394@google.com> <20201128080016.9132-1-hdanton@sina.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: <86f70001-fd2c-d17a-d79b-d2809a79ca0b@gmail.com> Date: Sun, 6 Dec 2020 13:31:12 +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: <20201128080016.9132-1-hdanton@sina.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/11/2020 08:00, Hillf Danton wrote: > On Fri, 27 Nov 2020 19:47:15 -0800 >> syzbot has found a reproducer for the following issue on: >> >> HEAD commit: 99c710c4 Merge tag 'platform-drivers-x86-v5.10-2' of git:/.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=12a77ddd500000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=c7a27a77f20fbc95 >> dashboard link: https://syzkaller.appspot.com/bug?extid=71c4697e27c99fddcf17 >> compiler: gcc (GCC) 10.1.0-syz 20200507 >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12d6161d500000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16f15e65500000 >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+71c4697e27c99fddcf17@syzkaller.appspotmail.com >> >> BUG: memory leak >> unreferenced object 0xffff888101401300 (size 168): >> comm "syz-executor355", pid 8461, jiffies 4294953658 (age 32.400s) >> hex dump (first 32 bytes): >> 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >> backtrace: >> [<00000000caa0de2b>] prepare_creds+0x25/0x390 kernel/cred.c:258 >> [<000000001821b99d>] copy_creds+0x3a/0x230 kernel/cred.c:358 >> [<0000000022c32914>] copy_process+0x661/0x24d0 kernel/fork.c:1971 >> [<00000000d3adca2d>] kernel_clone+0xf3/0x670 kernel/fork.c:2456 >> [<00000000d11b7286>] __do_sys_clone+0x76/0xa0 kernel/fork.c:2573 >> [<000000008280baad>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 >> [<00000000685d8cf0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> >> BUG: memory leak >> unreferenced object 0xffff88810b0a6f20 (size 32): >> comm "syz-executor355", pid 8461, jiffies 4294953658 (age 32.400s) >> hex dump (first 32 bytes): >> b0 6e 93 00 81 88 ff ff 00 00 00 00 00 00 00 00 .n.............. >> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >> backtrace: >> [<000000007d750ba1>] kmalloc include/linux/slab.h:557 [inline] >> [<000000007d750ba1>] kzalloc include/linux/slab.h:664 [inline] >> [<000000007d750ba1>] lsm_cred_alloc security/security.c:533 [inline] >> [<000000007d750ba1>] security_prepare_creds+0xa5/0xd0 security/security.c:1632 >> [<00000000ba63fcc7>] prepare_creds+0x277/0x390 kernel/cred.c:285 >> [<000000001821b99d>] copy_creds+0x3a/0x230 kernel/cred.c:358 >> [<0000000022c32914>] copy_process+0x661/0x24d0 kernel/fork.c:1971 >> [<00000000d3adca2d>] kernel_clone+0xf3/0x670 kernel/fork.c:2456 >> [<00000000d11b7286>] __do_sys_clone+0x76/0xa0 kernel/fork.c:2573 >> [<000000008280baad>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 >> [<00000000685d8cf0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Fail to spot the cred leak. >> >> BUG: memory leak >> unreferenced object 0xffff888101ea2200 (size 256): >> comm "syz-executor355", pid 8470, jiffies 4294953658 (age 32.400s) >> hex dump (first 32 bytes): >> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >> 20 59 03 01 81 88 ff ff 80 87 a8 10 81 88 ff ff Y.............. >> backtrace: >> [<000000002e0a7c5f>] kmem_cache_zalloc include/linux/slab.h:654 [inline] >> [<000000002e0a7c5f>] __alloc_file+0x1f/0x130 fs/file_table.c:101 >> [<000000001a55b73a>] alloc_empty_file+0x69/0x120 fs/file_table.c:151 >> [<00000000fb22349e>] alloc_file+0x33/0x1b0 fs/file_table.c:193 >> [<000000006e1465bb>] alloc_file_pseudo+0xb2/0x140 fs/file_table.c:233 >> [<000000007118092a>] anon_inode_getfile fs/anon_inodes.c:91 [inline] >> [<000000007118092a>] anon_inode_getfile+0xaa/0x120 fs/anon_inodes.c:74 >> [<000000002ae99012>] io_uring_get_fd fs/io_uring.c:9198 [inline] >> [<000000002ae99012>] io_uring_create fs/io_uring.c:9377 [inline] >> [<000000002ae99012>] io_uring_setup+0x1125/0x1630 fs/io_uring.c:9411 >> [<000000008280baad>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 >> [<00000000685d8cf0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> > Put file as part of the error handling after getting a new one. Looks genuine to me, would you send a real patch? > > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -9182,6 +9182,7 @@ static int io_uring_get_fd(struct io_rin > { > struct file *file; > int ret; > + int fd; > > #if defined(CONFIG_UNIX) > ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP, > @@ -9190,28 +9191,29 @@ static int io_uring_get_fd(struct io_rin > return ret; > #endif > > - ret = get_unused_fd_flags(O_RDWR | O_CLOEXEC); > + ret = fd = get_unused_fd_flags(O_RDWR | O_CLOEXEC); > if (ret < 0) > goto err; > > file = anon_inode_getfile("[io_uring]", &io_uring_fops, ctx, > O_RDWR | O_CLOEXEC); > if (IS_ERR(file)) { > -err_fd: > - put_unused_fd(ret); > ret = PTR_ERR(file); > + put_unused_fd(fd); > goto err; > } > > #if defined(CONFIG_UNIX) > ctx->ring_sock->file = file; > #endif > - if (unlikely(io_uring_add_task_file(ctx, file))) { > - file = ERR_PTR(-ENOMEM); > - goto err_fd; > + ret = io_uring_add_task_file(ctx, file); > + if (ret) { > + fput(file); > + put_unused_fd(fd); > + goto err; > } > fd_install(ret, file); > - return ret; > + return 0; > err: > #if defined(CONFIG_UNIX) > sock_release(ctx->ring_sock); > -- Pavel Begunkov