Re: [Xen-devel] [PATCH V2] libxc: Prevent NULL pointer dereference in stdiostream_vmessage()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 07/07/15 16:48, Jennifer Herbert wrote:
> Unlikely that it may seem localtime_r could fail, which would result in a
> null pointer dereference.  In this case, it shoud log the errno, (instead of
> the date/time), and and continue its logging, as this is still useful.
>
> Signed-off-by: Jennifer Herbert <jennifer.herbert@xxxxxxxxxx>
> ---
>  tools/libxc/xtl_logger_stdio.c |   11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/tools/libxc/xtl_logger_stdio.c b/tools/libxc/xtl_logger_stdio.c
> index d8646e0..5569c50 100644
> --- a/tools/libxc/xtl_logger_stdio.c
> +++ b/tools/libxc/xtl_logger_stdio.c
> @@ -61,10 +61,13 @@ static void stdiostream_vmessage(xentoollog_logger 
> *logger_in,
>          struct tm lt_buf;
>          time_t now = time(0);
>          struct tm *lt= localtime_r(&now, &lt_buf);
> -        fprintf(lg->f, "%04d-%02d-%02d %02d:%02d:%02d %s ",
> -                lt->tm_year+1900, lt->tm_mon+1, lt->tm_mday,
> -                lt->tm_hour, lt->tm_min, lt->tm_sec,
> -                tzname[!!lt->tm_isdst]);
> +        if (lt != NULL)
> +            fprintf(lg->f, "%04d-%02d-%02d %02d:%02d:%02d %s ",
> +                    lt->tm_year+1900, lt->tm_mon+1, lt->tm_mday,
> +                    lt->tm_hour, lt->tm_min, lt->tm_sec,
> +                    tzname[!!lt->tm_isdst]);
> +        else
> +            fprintf(lg-f, "[localtime_r failed: %d] ", errno);

lg->f ?

~Andrew

>      }
>      if (lg->flags & XTL_STDIOSTREAM_SHOW_PID)
>          fprintf(lg->f, "[%lu] ", (unsigned long)getpid());


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