On Mon, Sep 23, 2013 at 10:18:12AM +0200, Geert Uytterhoeven wrote:
> When calling locate_hole() with "hole_size" equal to the size of an
> available memory block, it fails to use that memory block.
>
> "end" and "hole_max" point to the last byte within the range, hence
> - "size = end - start" is one less than "hole_size",
> - "hole_base + hole_size" is one more than "hole_max".
>
> Subtract one from "hole_size" when doing the comparison (adding 1 to "size"
> could overflow in case of one big range covering the whole address space).
>
> Signed-off-by: Geert Uytterhoeven <geert at linux-m68k.org>
> ---
> Question:
> The code no longer handles the case where "hole_size" is zero.
> Should this be rejected (like is done for a zero "hole_end" at the top
> of the function), or accepted?
Either way would be fine by me though I lean towards accepting it.
>
> kexec/kexec.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kexec/kexec.c b/kexec/kexec.c
> index 2b98ef0..eafd6c2 100644
> --- a/kexec/kexec.c
> +++ b/kexec/kexec.c
> @@ -270,7 +270,7 @@ unsigned long locate_hole(struct kexec_info *info,
> }
> /* Is there enough space left so we can use it? */
> size = end - start;
> - if (size >= hole_size) {
> + if (size >= hole_size - 1) {
> if (hole_end > 0) {
> hole_base = start;
> break;
> @@ -286,7 +286,7 @@ unsigned long locate_hole(struct kexec_info *info,
> "0x%lx bytes...\n", hole_size);
> return ULONG_MAX;
> }
> - if ((hole_base + hole_size) > hole_max) {
> + if ((hole_base + hole_size - 1) > hole_max) {
> fprintf(stderr, "Could not find a free area of memory below: "
> "0x%lx...\n", hole_max);
> return ULONG_MAX;
> --
> 1.7.9.5
>
