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

[Laurent Vivier <laurent@vivier.eu>]

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 <lvivier@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>  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?

Thanks,
Laurent