Re: [PATCH] scsi: core: initialize cmd->cmnd before it is used

[Bart Van Assche]

On 11/1/21 1:13 PM, Tadeusz Struk wrote:
> On 11/1/21 13:06, Bart Van Assche wrote:
> > This patch is a duplicate and has been posted before.
> >
> > Please take a look at https://lore.kernel.org/linux-scsi/20210904064534.1919476-1-qiulaibin@xxxxxxxxxx/.
> >  From the replies to that email:
> > "> Thinking further about this: is there any code left that depends on
> >  > scsi_setup_scsi_cmnd() setting cmd->cmd_len? Can the cmd->cmd_len
> >  > assignment be removed from scsi_setup_scsi_cmnd()?
> >
> > cmd_len should never be 0 now, so I think we can remove it."
>
> Thanks for quick response, but I'm not sure if statement
> "cmd_len should never be 0 now" is correct, because the cmd_len is
> in fact equal to 0 here and this BUG can be triggered on mainline, 5.14,
> and 5.10 stable kernels.

(+Doug Gilbert)

One of the functions in the call stack in the first message of this email
thread is sg_io(). I am not aware of any documentation that specifies whether
it is valid to set cmd_len in the sg_io header to zero. My opinion is that
the SG_IO implementation should either reject cmd_len == 0 or set cmd_len
to a valid value if it is zero.

Bart.