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Subject: Re: [PATCH] io_uring: fix file leak on creating io ctx
From:   Jens Axboe <axboe@kernel.dk>
To:     Hillf Danton <hdanton@sina.com>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     io-uring@vger.kernel.org, syzkaller-bugs@googlegroups.com,
        syzbot+71c4697e27c99fddcf17@syzkaller.appspotmail.com,
        Pavel Begunkov <asml.silence@gmail.com>
References: <20201207081558.2361-1-hdanton@sina.com>
 <13bd991a-be45-6521-655d-74b8d810b714@kernel.dk>
Message-ID: <848ad126-c4f7-6dba-24da-d7e29cbcfb67@kernel.dk>
Date:   Mon, 7 Dec 2020 08:42:25 -0700
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On 12/7/20 8:04 AM, Jens Axboe wrote:
> On 12/7/20 1:15 AM, Hillf Danton wrote:
>> Put file as part of error handling when setting up io ctx to fix
>> memory leak like the following one.
>>
>>    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
> 
> Applied for 5.10, thanks.

I take that back, this patch is totally broken. Please test your patches
before sending them out, this cannot have been even put through the most
basic of tests.

-- 
Jens Axboe