Re: [Qemu-trivial] [PATCH for 2.10 27/35] syscall: fix dereference of undefined pointer

[Philippe Mathieu-Daudé]

On 07/24/2017 04:33 PM, Laurent Vivier wrote:
> Le 24/07/2017 à 20:27, Philippe Mathieu-Daudé a écrit :
> > Clang's scan-build-5.0 reports:
> >
> > linux-user/syscall.c:5581:9: warning: Dereference of undefined pointer value
> >      if (*host_rt_dev_ptr != 0) {
> >          ^~~~~~~~~~~~~~~~
> >
> > Reported-by: Clang Static Analyzer
> > Suggested-by: Laurent Vivier <address@hidden>
> > Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> > ---
> >   linux-user/syscall.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> > index fcd20fa276..e79b5baec4 100644
> > --- a/linux-user/syscall.c
> > +++ b/linux-user/syscall.c
> > @@ -5524,7 +5524,7 @@ static abi_long do_ioctl_rt(const IOCTLEntry *ie, uint8_t 
> > *buf_temp,
> >       int target_size;
> >       void *argptr;
> >       abi_ulong *target_rt_dev_ptr;
> > -    unsigned long *host_rt_dev_ptr;
> > +    unsigned long *host_rt_dev_ptr = NULL;
> >       abi_long ret;
> >       int i;
> >   
> > @@ -5570,6 +5570,7 @@ static abi_long do_ioctl_rt(const IOCTLEntry *ie, uint8_t *buf_temp,
> >       unlock_user(argptr, arg, 0);
> >   
> >       ret = get_errno(safe_ioctl(fd, ie->host_cmd, buf_temp));
> > +    assert(host_rt_dev_ptr);
> >       if (*host_rt_dev_ptr != 0) {
> >           unlock_user((void *)*host_rt_dev_ptr,
> >                       *target_rt_dev_ptr, 0);
>
> I think if you add the assert you should not have to add the "= NULL".
> Could you check?

Indeed!

Thanks :)

Phil.