Re: [bug report] infiniband/hw/mthca: ancient uninitialized variable

[Leon Romanovsky <leon@kernel.org>]

On Thu, Nov 02, 2023 at 10:50:36AM +0300, Dan Carpenter wrote:
> [ This code is very old, but it's also very obviously buggy.  Does
>   anyone know what a good default "out =" value should be? - dan ]
> 
> Hello Linus Torvalds,

Hi,

> 
> The patch 1da177e4c3f4: "Linux-2.6.12-rc2" from Apr 16, 2005
> (linux-next), leads to the following Smatch static checker warning:
> 
> 	drivers/infiniband/hw/mthca/mthca_cmd.c:644 mthca_SYS_EN()
> 	error: uninitialized symbol 'out'.

Thanks for the report, I'll send a patch after merge window.

> 
> drivers/infiniband/hw/mthca/mthca_cmd.c
>     636 int mthca_SYS_EN(struct mthca_dev *dev)
>     637 {
>     638         u64 out;
>     639         int ret;
>     640 
>     641         ret = mthca_cmd_imm(dev, 0, &out, 0, 0, CMD_SYS_EN, CMD_TIME_CLASS_D);
> 
> We pass out here and it gets used without being initialized.
> 
>         err = mthca_cmd_post(dev, in_param,
>                              out_param ? *out_param : 0,
>                                          ^^^^^^^^^^
>                              in_modifier, op_modifier,
>                              op, context->token, 1);
> 
> It's the same in mthca_cmd_wait() and mthca_cmd_poll().
> 
>     642 
>     643         if (ret == -ENOMEM)
> --> 644                 mthca_warn(dev, "SYS_EN DDR error: syn=%x, sock=%d, "
>     645                            "sladdr=%d, SPD source=%s\n",
>     646                            (int) (out >> 6) & 0xf, (int) (out >> 4) & 3,
>     647                            (int) (out >> 1) & 7, (int) out & 1 ? "NVMEM" : "DIMM");
>     648 
>     649         return ret;
>     650 }
> 
> regards,
> dan carpenter