On 4/9/19 7:40 PM, Markus Armbruster wrote:
> If the value of get_image_size() exceeds INT_MAX / 2 - 10000, the
> computation of @dt_size overflows to a negative number, which then
> gets converted to a very large size_t for g_malloc0() and
> load_image_size(). In the (fortunately improbable) case g_malloc0()
> succeeds and load_image_size() survives, we'd assign the negative
> number to *sizep. What that would do to the callers I can't say, but
> it's unlikely to be good.
>
> Fix by rejecting images whose size would overflow.
>
> Signed-off-by: Markus Armbruster <arm...@redhat.com>
> ---
> device_tree.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/device_tree.c b/device_tree.c
> index 296278e12a..f8b46b3c73 100644
> --- a/device_tree.c
> +++ b/device_tree.c
> @@ -84,6 +84,10 @@ void *load_device_tree(const char *filename_path, int
> *sizep)
> filename_path);
> goto fail;
> }
> + if (dt_size > INT_MAX / 2 - 10000) {
We should avoid magic number duplication.
That said, this patch looks safe.
Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>
BTW how did you figure that out?
> + error_report("Device tree file '%s' is too large", filename_path);
> + goto fail;
> + }
>
> /* Expand to 2x size to give enough room for manipulation. */
> dt_size += 10000;
>
