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

[Pan Nengyuan]

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.

> 
> Paolo
> 
> .
>