Re: [PATCH] scsi: Silence gcc warning

[Laurent Vivier]

Le 08/03/2021 à 20:54, Eric Blake a écrit :
> Adding qemu-trivial in cc.
> 
> On 2/9/21 9:44 AM, Philippe Mathieu-Daudé wrote:
>> On 2/9/21 4:23 PM, Eric Blake wrote:
>>> On Fedora 33, gcc 10.2.1 notes that scsi_cdb_length(buf) can set
>>> len==-1, which in turn overflows g_malloc():
>>>
>>> [5/5] Linking target qemu-system-x86_64
>>> In function ‘scsi_disk_new_request_dump’,
>>>     inlined from ‘scsi_new_request’ at ../hw/scsi/scsi-disk.c:2608:9:
>>> ../hw/scsi/scsi-disk.c:2582:19: warning: argument 1 value 
>>> ‘18446744073709551612’ exceeds maximum object size 9223372036854775807 
>>> [-Walloc-size-larger-than=]
>>>  2582 |     line_buffer = g_malloc(len * 5 + 1);
>>>       |                   ^
>>>
>>> Silence it with a decent assertion, since we only convert a buffer to
>>> bytes when we have a valid cdb length.
>>>
>>> Signed-off-by: Eric Blake <eblake@redhat.com>
>>> ---
>>>  hw/scsi/scsi-disk.c | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
>>> index ed52fcd49ff0..b3311a5657b7 100644
>>> --- a/hw/scsi/scsi-disk.c
>>> +++ b/hw/scsi/scsi-disk.c
>>> @@ -2579,6 +2579,7 @@ static void scsi_disk_new_request_dump(uint32_t lun, 
>>> uint32_t tag, uint8_t *buf)
>>>      int len = scsi_cdb_length(buf);
>>>      char *line_buffer, *p;
>>>
>>> +    assert(len > 0 && len <= 16);
>>>      line_buffer = g_malloc(len * 5 + 1);
>>>
>>>      for (i = 0, p = line_buffer; i < len; i++) {
>>>
>>
>> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>>
> 

Applied to my trivial-patches branch.

Thanks,
Laurent