linux-kernel - Re: [PATCH][next] habanalabs/gaudi: Fix uninitialized return code rc when read size is zero

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Date:   Thu, 15 Apr 2021 10:08:26 +0300
From:   Oded Gabbay <oded.gabbay@...il.com>
To:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Colin King <colin.king@...onical.com>
Cc:     Oded Gabbay <ogabbay@...nel.org>, Ofir Bitton <obitton@...ana.ai>,
        kernel-janitors@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][next] habanalabs/gaudi: Fix uninitialized return code rc
 when read size is zero

On Mon, Apr 12, 2021 at 9:41 PM Arnd Bergmann <arnd@...db.de> wrote:
>
> On Mon, Apr 12, 2021 at 6:11 PM Colin King <colin.king@...onical.com> wrote:
> >
> > From: Colin Ian King <colin.king@...onical.com>
> >
> > In the case where size is zero the while loop never assigns rc and the
> > return value is uninitialized. Fix this by initializing rc to zero.
> >
> > Addresses-Coverity: ("Uninitialized scalar variable")
> > Fixes: 639781dcab82 ("habanalabs/gaudi: add debugfs to DMA from the device")
> > Signed-off-by: Colin Ian King <colin.king@...onical.com>
> > ---
> >  drivers/misc/habanalabs/gaudi/gaudi.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/misc/habanalabs/gaudi/gaudi.c b/drivers/misc/habanalabs/gaudi/gaudi.c
> > index 8730b691ec61..b751652f80a8 100644
> > --- a/drivers/misc/habanalabs/gaudi/gaudi.c
> > +++ b/drivers/misc/habanalabs/gaudi/gaudi.c
> > @@ -6252,7 +6252,7 @@ static int gaudi_debugfs_read_dma(struct hl_device *hdev, u64 addr, u32 size,
> >         dma_addr_t dma_addr;
> >         void *kernel_addr;
> >         bool is_eng_idle;
> > -       int rc, dma_id;
> > +       int rc = 0, dma_id;
> >
> >         kernel_addr = hdev->asic_funcs->asic_dma_alloc_coherent(
> >                                                 hdev, SZ_2M,
>
>
> In general, I don't like adding initializations during the declaration as that
> tends to hide warnings for the cases where a later initialization is
> missing. In this case it looks correct though.
>
> Acked-by: Arnd Bergmann <arnd@...db.de>

I don't mind taking this patch for eliminating the warning but fyi,
the caller function (hl_dma_size_write) checks that the size is not
zero. If the size is zero, we never reach this function.

Greg, do you mind applying it directly to your -next branch ? I don't
have anything pending and I'm too lazy sending a pull request on a
single patch ;)

Reviewed-by: Oded Gabbay <ogabbay@...nel.org>

Thanks,
Oded