[PATCHv3] staging: Check for Null allocated skb in fw_download_code

[Jeff Haran]

> -----Original Message-----
> From: kernelnewbies-bounces at kernelnewbies.org [mailto:kernelnewbies-bounces at kernelnewbies.org] On Behalf Of Nick Krause
> Sent: Tuesday, August 12, 2014 1:20 PM
> To: kernelnewbies
> Subject: Re: [PATCHv3] staging: Check for Null allocated skb in fw_download_code
> 
> On Tue, Aug 12, 2014 at 4:18 PM, Nicholas Krause <xerofoify at gmail.com> wrote:
> > I am fixing the bug entry , https://bugzilla.kernel.org/show_bug.cgi?id=60461.
> > This entry states that we are not checking the skb allocated in fw_download_code
> > for NULL and after checking it ,I fixed it to check for the NULL value before
> > returning false and exiting fw_download_code cleanly. In additon I removed the
> > variable, rt_status as it's easier to read this function's return value with
> > just true or false and rt status is a unneeded variable for the bool return
> > of this function.
> >
> > Signed-off-by: Nicholas Krause <xerofoify at gmail.com>
> > ---
> >  drivers/staging/rtl8192e/rtl8192e/r8192E_firmware.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/staging/rtl8192e/rtl8192e/r8192E_firmware.c b/drivers/staging/rtl8192e/rtl8192e/r8192E_firmware.c
> > index 1a95d1f..66d83f8 100644
> > --- a/drivers/staging/rtl8192e/rtl8192e/r8192E_firmware.c
> > +++ b/drivers/staging/rtl8192e/rtl8192e/r8192E_firmware.c
> > @@ -36,7 +36,6 @@ static bool fw_download_code(struct net_device *dev, u8 *code_virtual_address,
> >                              u32 buffer_len)
> >  {
> >         struct r8192_priv *priv = rtllib_priv(dev);
> > -       bool                rt_status = true;
> >         u16                 frag_threshold;
> >         u16                 frag_length, frag_offset = 0;
> >         int                 i;
> > @@ -61,6 +60,8 @@ static bool fw_download_code(struct net_device *dev, u8 *code_virtual_address,
> >                 }
> >
> >                 skb  = dev_alloc_skb(frag_length + 4);
> > +               if (skb == NULL)
> > +                       return false;
> >                 memcpy((unsigned char *)(skb->cb), &dev, sizeof(dev));
> >                 tcb_desc = (struct cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
> >                 tcb_desc->queue_index = TXCMD_QUEUE;
> > @@ -99,7 +100,7 @@ static bool fw_download_code(struct net_device *dev, u8 *code_virtual_address,
> >
> >         write_nic_byte(dev, TPPoll, TPPoll_CQ);
> >
> > -       return rt_status;
> > +       return true;
> >  }
> >
> >  static bool CPUcheck_maincodeok_turnonCPU(struct net_device *dev)
> > --
> > 1.9.1
> >
> 
> I am trying to get this patch merged and after my issues with the
> kernel community, I can't get this into the mainline.
> If someone wants to send it out for me and state it's from me that
> would be great.
> Nick

While the avoidance of dereferencing NULL pointers in the kernel is a laudable goal, what will be the effect of the call to write_nic_byte() at the end of the function not happening should the call to dev_alloc_skb() return NULL?

Jeff Haran