linux-kernel - Re: [syzbot] memory leak in io_sqe_buffers

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Message-ID: <a443802d-ed33-61d8-2fac-f525d59ee531@gmail.com>
Date:   Fri, 30 Apr 2021 13:19:31 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Hillf Danton <hdanton@...a.com>,
        syzbot <syzbot+0f32d05d8b6cd8d7ea3e@...kaller.appspotmail.com>
Cc:     axboe@...nel.dk, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] memory leak in io_sqe_buffers_register

On 4/30/21 8:51 AM, Hillf Danton wrote:
> On Thu, 29 Apr 2021 23:55:21 -0700
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit:    d2b6f8a1 Merge tag 'xfs-5.13-merge-3' of git://git.kernel...
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=173639a3d00000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=337dc545ba10a406
>> dashboard link: https://syzkaller.appspot.com/bug?extid=0f32d05d8b6cd8d7ea3e
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14df6ba3d00000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12815385d00000
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+0f32d05d8b6cd8d7ea3e@...kaller.appspotmail.com
>>
>> Debian GNU/Linux 9 syzkaller ttyS0
>> Warning: Permanently added '10.128.1.62' (ECDSA) to the list of known hosts.
>> executing program
>> executing program
>> executing program
>> BUG: memory leak
>> unreferenced object 0xffff8881123bf0a0 (size 32):
>>   comm "syz-executor557", pid 8384, jiffies 4294946143 (age 12.360s)
>>   hex dump (first 32 bytes):
>>     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 00  ................
>>   backtrace:
>>     [<ffffffff81469b71>] kmalloc_node include/linux/slab.h:579 [inline]
>>     [<ffffffff81469b71>] kvmalloc_node+0x61/0xf0 mm/util.c:587
>>     [<ffffffff815f0b3f>] kvmalloc include/linux/mm.h:795 [inline]
>>     [<ffffffff815f0b3f>] kvmalloc_array include/linux/mm.h:813 [inline]
>>     [<ffffffff815f0b3f>] kvcalloc include/linux/mm.h:818 [inline]
>>     [<ffffffff815f0b3f>] io_rsrc_data_alloc+0x4f/0xc0 fs/io_uring.c:7164
>>     [<ffffffff815f26d8>] io_sqe_buffers_register+0x98/0x3d0 fs/io_uring.c:8383
>>     [<ffffffff815f84a7>] __io_uring_register+0xf67/0x18c0 fs/io_uring.c:9986
>>     [<ffffffff81609222>] __do_sys_io_uring_register fs/io_uring.c:10091 [inline]
>>     [<ffffffff81609222>] __se_sys_io_uring_register fs/io_uring.c:10071 [inline]
>>     [<ffffffff81609222>] __x64_sys_io_uring_register+0x112/0x230 fs/io_uring.c:10071
>>     [<ffffffff842f616a>] do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
>>     [<ffffffff84400068>] entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> Free rsrc data with the routine available.

right, only the other sent patch by Zqiang is more complete

> 
> +++ x/fs/io_uring.c
> @@ -8385,7 +8385,7 @@ static int io_sqe_buffers_register(struc
>  		return -ENOMEM;
>  	ret = io_buffers_map_alloc(ctx, nr_args);
>  	if (ret) {
> -		kfree(data);
> +		io_rsrc_data_free(data);
>  		return ret;
>  	}
>  
> 

-- 
Pavel Begunkov