Re: [PATCH v2] scsi-disk: define props in scsi_block_disk to avoid memleaks

[Pan Nengyuan]

Hi Paolo,

On 2/19/2020 3:52 PM, Pan Nengyuan wrote:
> 
> 
> On 1/22/2020 1:05 AM, Paolo Bonzini wrote:
>> On 14/01/20 10:16, address@hidden wrote:
>>> From: Pan Nengyuan <address@hidden>
>>>
>>> scsi_block_realize() use scsi_realize() to init some props, but
>>> these props is not defined in scsi_block_disk_properties, so they will
>>> not be freed.
>>>
>>> This patch defines these prop in scsi_block_disk_properties and aslo
>>> calls scsi_unrealize to avoid memleaks, the leak stack as
>>> follow(it's easy to reproduce by attaching/detaching scsi-block-disks):
>>>
>>> =================================================================
>>> ==qemu-system-x86_64==32195==ERROR: LeakSanitizer: detected memory leaks
>>>
>>> Direct leak of 57 byte(s) in 3 object(s) allocated from:
>>>   #0 0x7f19f8bed768 (/lib64/libasan.so.5+0xef768)  ??:?
>>>   #1 0x7f19f64d9445 (/lib64/libglib-2.0.so.0+0x52445)  ??:?
>>>   #2 0x7f19f64f2d92 (/lib64/libglib-2.0.so.0+0x6bd92)  ??:?
>>>   #3 0x55975366e596 (qemu-system-x86_64+0x35c0596)  
>>> /mnt/sdb/qemu/hw/scsi/scsi-disk.c:2399
>>>   #4 0x559753671201 (emu-system-x86_64+0x35c3201)  
>>> /mnt/sdb/qemu/hw/scsi/scsi-disk.c:2681
>>>   #5 0x559753687e3e (qemu-system-x86_64+0x35d9e3e)  
>>> /mnt/sdb/qemu/hw/scsi/scsi-bus.c:58
>>>   #6 0x55975368ac44 (qemu-system-x86_64+0x35dcc44)  
>>> /mnt/sdb/qemu/hw/scsi/scsi-bus.c:216
>>>   #7 0x5597532a7840 (qemu-system-x86_64+0x31f9840)  
>>> /mnt/sdb/qemu/hw/core/qdev.c:876
>>>
>>> Direct leak of 15 byte(s) in 3 object(s) allocated from:
>>>   #0 0x7f19f8bed768 (/lib64/libasan.so.5+0xef768)  ??:?
>>>   #1 0x7f19f64d9445 (/lib64/libglib-2.0.so.0+0x52445)  ??:?
>>>   #2 0x7f19f64f2d92 (/lib64/libglib-2.0.so.0+0x6bd92)  ??:?
>>>   #3 0x55975366e06f (qemu-system-x86_64+0x35c006f)  
>>> /mnt/sdb/qemu/hw/scsi/scsi-disk.c:2388
>>>   #4 0x559753671201 (qemu-system-x86_64+0x35c3201)  
>>> /mnt/sdb/qemu/hw/scsi/scsi-disk.c:2681
>>>   #5 0x559753687e3e (qemu-system-x86_64+0x35d9e3e)  
>>> /mnt/sdb/qemu/hw/scsi/scsi-bus.c:58
>>>   #6 0x55975368ac44 (qemu-system-x86_64+0x35dcc44)  
>>> /mnt/sdb/qemu/hw/scsi/scsi-bus.c:216
>>>
>>> @@ -3079,9 +3080,8 @@ static const TypeInfo scsi_cd_info = {
>>>  
>>>  #ifdef __linux__
>>>  static Property scsi_block_properties[] = {
>>> -    DEFINE_BLOCK_ERROR_PROPERTIES(SCSIDiskState, qdev.conf),         \
>>> +    DEFINE_SCSI_DISK_PROPERTIES(),.
>> The properties defined there shouldn't apply to scsi-block.
>>
>> Can you explain what exactly is being leaked?
> 
> Ohh, I'm sorry, I missed this email and reply it so late.
> 
> When we attach a scsi-block disk, the props(version/vender/device_id) are 
> malloced in scsi_realize() which it's called by scsi_block_realize(),
> but we don't define these props in scsi_block_properties. So these props will 
> not be released when we detach the scsi-block disk.
> 
> This patch will reuse scsi_disk_properties to define those props in 
> scsi_block_properties to fix it.
> Similarly to scsi_hd, this patch aslo set unrealize to call 
> del_boot_device_lchs().
> 
> Thanks.
> 

Maybe you missed this patch due to my late reply. Actually it will cause a 
memleak when we attach/detach a scsi-block disk.

Reproducer:
(qemu) device_add virtio-scsi-pci,id=scsi1,bus=pci.0,addr=0x7
(qemu) drive_add 1 
file=/dev/sdc,format=raw,if=none,id=drive-scsi1-0-0-12,cache=none,aio=native
OK
(qemu) device_add 
scsi-block,bus=scsi1.0,channel=0,scsi-id=0,lun=10,share-rw=on,drive=drive-scsi1-0-0-12,id=scsi1-0-0-10
(qemu) device_del scsi1-0-0-10
(qemu) drive_del drive-scsi1-0-0-12

I'm not sure why the properties defined shouldn't be applied, can you give some 
more suggestions?

Thanks.

>>
>> Paolo
>>
>> .
>>