Re: [Qemu-devel] [PATCH] scsi-disk: fix crash on VERIFY command

[Zhang Qian]

At 2017-01-03 17:38:49, Paolo Bonzini <address@hidden> wrote:
>
>
>On 03/01/2017 09:12, Zhang Qian wrote:
>> yes, you are right.
>> The scenarios of problem is
>> a scsi-disk object receives VERIFY command with BYTCHK bit being zero,
>> scsi_block_is_passthrough returns false and finally scsi-block uses
>> scsi_disk_dma_command for
>> VERIFY. So the mode is set to SCSI_XFER_NONE.
>> In scsi_req_continue, scsi_read_data function is called.
>
>Uhm, is the fix simply
>
>diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
>index bdd1e5f..c080888 100644
>--- a/hw/scsi/scsi-disk.c
>+++ b/hw/scsi/scsi-disk.c
>@@ -2701,7 +2701,7 @@ static bool scsi_block_is_passthrough(SCSIDiskState *s, 
>uint8_t *buf)
>          * for the number of logical blocks specified in the length
>          * field).  For other modes, do not use scatter/gather operation.
>          */
>-        if ((buf[1] & 6) != 2) {
>+        if ((buf[1] & 6) == 2) {
>             return false;
>         }
>         break;
>
>then?


I verified your patch, it is ok.


but  why not use (buf[1] & 2) == 2  ?


>Thanks,
>
>Paolo