Re: [PULL 23/35] hw/intc: Rework Loongson LIOINTC

[BALATON Zoltan]

On Sun, 10 Jan 2021, Philippe Mathieu-Daudé wrote:
> Hi Peter, Huacai,
>
> On 1/10/21 8:49 PM, Peter Maydell wrote:
> > On Sun, 3 Jan 2021 at 21:11, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> > > From: Huacai Chen <chenhuacai@kernel.org>
> > >
> > > As suggested by Philippe Mathieu-Daudé, rework Loongson's liointc:
> > > 1, Move macro definitions to loongson_liointc.h;
> > > 2, Remove magic values and use macros instead;
> > > 3, Replace dead D() code by trace events.
> > >
> > > Suggested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> > > Signed-off-by: Huacai Chen <chenhuacai@kernel.org>
> > > Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> > > Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> > > Message-Id: <20201221110538.3186646-2-chenhuacai@kernel.org>
> > > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> > > ---
> > >  include/hw/intc/loongson_liointc.h | 22 ++++++++++++++++++
> > >  hw/intc/loongson_liointc.c         | 36 +++++++++++++-----------------
> > >  2 files changed, 38 insertions(+), 20 deletions(-)
> > >  create mode 100644 include/hw/intc/loongson_liointc.h
> >
> > Hi; Coverity complains about a possible array overrun
> > in this commit:
> >
> >
> > > @@ -40,13 +39,10 @@
> > >  #define R_IEN                   0x24
> > >  #define R_IEN_SET               0x28
> > >  #define R_IEN_CLR               0x2c
> > > -#define R_PERCORE_ISR(x)        (0x40 + 0x8 * x)
> > > +#define R_ISR_SIZE              0x8
> > > +#define R_START                 0x40
> > >  #define R_END                   0x64
> > >
> > > -#define TYPE_LOONGSON_LIOINTC "loongson.liointc"
> > > -DECLARE_INSTANCE_CHECKER(struct loongson_liointc, LOONGSON_LIOINTC,
> > > -                         TYPE_LOONGSON_LIOINTC)
> > > -
> > >  struct loongson_liointc {
> > >      SysBusDevice parent_obj;
> > >
> > > @@ -123,14 +119,13 @@ liointc_read(void *opaque, hwaddr addr, unsigned int size)
> > >          goto out;
> > >      }
> > >
> > > -    /* Rest is 4 byte */
> > > +    /* Rest are 4 bytes */
> > >      if (size != 4 || (addr % 4)) {
> > >          goto out;
> > >      }

Expanding macros in the following:

> > > -    if (addr >= R_PERCORE_ISR(0) &&
> > > -        addr < R_PERCORE_ISR(NUM_CORES)) {
> > > -        int core = (addr - R_PERCORE_ISR(0)) / 8;

if (addr >= (0x40 + 0x8 * 0) && addr < (0x40 + 0x8 * 4))
->
if (addr >= 0x40 && addr < 0x60)
int core = (addr - 0x40) / 8;


> > > +    if (addr >= R_START && addr < R_END) {
> > > +        int core = (addr - R_START) / R_ISR_SIZE;

if (addr >= 0x40 && addr < 0x64)
int core = (addr - 0x40) / 0x8;

R_END seems to be off by 4 in the above. Should it be 0x60?

Regards,
BALATON Zoltan

> > R_END is 0x64 and R_START is 0x40, so if addr is 0x60
> > then addr - R_START is 0x32 and so core here is 4.
> > However p->per_core_isr[] only has 4 entries, so this will
> > be off the end of the array.
> >
> > This is CID 1438965.
> >
> > >          r = p->per_core_isr[core];
> > >          goto out;
> > >      }
> >
> > > -    if (addr >= R_PERCORE_ISR(0) &&
> > > -        addr < R_PERCORE_ISR(NUM_CORES)) {
> > > -        int core = (addr - R_PERCORE_ISR(0)) / 8;
> > > +    if (addr >= R_START && addr < R_END) {
> > > +        int core = (addr - R_START) / R_ISR_SIZE;
> > >          p->per_core_isr[core] = value;
> > >          goto out;
> > >      }
> >
> > Same thing here, CID 1438967.
>
> Thanks Peter.
>
> Huacai, can you have a look please?
>
> Thanks,
>
> Phil.