Re: [Qemu-devel] [PATCH] xilinx_spips: Correct usage of an uninitialized local variable

[francisco iglesias]

On Tuesday, 16 January 2018, Peter Maydell <address@hidden> wrote:

> On 14 January 2018 at 22:55, Francisco Iglesias
> <address@hidden> wrote:
> > Coverity found that the variable tx_rx in the function
> > xilinx_spips_flush_txfifo was being used uninitialized (CID 1383841).
> This
> > patch corrects this by always initializing tx_rx to zeros.
> >
> > Signed-off-by: Francisco Iglesias <address@hidden>
> > ---
> >  hw/ssi/xilinx_spips.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/ssi/xilinx_spips.c b/hw/ssi/xilinx_spips.c
> > index d8187fa..77e1bbe 100644
> > --- a/hw/ssi/xilinx_spips.c
> > +++ b/hw/ssi/xilinx_spips.c
> > @@ -210,6 +210,8 @@
> >  #define SNOOP_NONE 0xEE
> >  #define SNOOP_STRIPING 0
> >
> > +#define MAX_NUM_EFFECTIVE_BUSSES 2
> > +
> >  static inline int num_effective_busses(XilinxSPIPS *s)
> >  {
> >      return (s->regs[R_LQSPI_CFG] & LQSPI_CFG_SEP_BUS &&
> > @@ -573,7 +575,7 @@ static void xilinx_spips_flush_txfifo(XilinxSPIPS
> *s)
> >      for (;;) {
> >          int i;
> >          uint8_t tx = 0;
> > -        uint8_t tx_rx[num_effective_busses(s)];
> > +        uint8_t tx_rx[MAX_NUM_EFFECTIVE_BUSSES] = { 0 };
> >          uint8_t dummy_cycles = 0;
> >          uint8_t addr_length;
>
> It doesn't look like your device's realize method is sanity checking
> the num_busses property, so this change means that the user can
> make the device model segfault by passing it a num_busses property
> value larger than 2...
>
> thanks
> -- PMM
>

Hi Peter,

Thank you very much for reviewing the patch and I apologize for missing out
on above. I'll look into a correction and create a new version of the patch.

Best regards,
Francisco Iglesias