On 12/16/23 at 12:18pm, Yuntao Wang wrote:
> The end parameter received by kimage_is_destination_range() should be the
> last valid byte address of the target memory segment plus 1. However, in
> the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
> the corresponding value passed to kimage_is_destination_range() is the last
> valid byte address of the target memory segment, which is 1 less.
>
> There are two ways to fix this bug. We can either correct the logic of the
> locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions, or we
> can fix kimage_is_destination_range() by making the end parameter represent
> the last valid byte address of the target memory segment. Here, we choose
> the second approach.
>
> Due to the modification to kimage_is_destination_range(), we also need to
> adjust its callers, such as kimage_alloc_normal_control_pages() and
> kimage_alloc_page().
>
> Signed-off-by: Yuntao Wang <ytcoode@xxxxxxxxx>
> ---
> v1->v2:
> Fix this issue using the approach suggested by Eric and Baoquan.
>
> As this patch is independent of the other patches in this series, I sent
> out the v2 patch separately. If it's inconvenient for anyone, I can
> resend the entire series again.
>
> kernel/kexec_core.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index be5642a4ec49..5991b3ae072c 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -276,8 +276,8 @@ int kimage_is_destination_range(struct kimage *image,
> unsigned long mstart, mend;
>
> mstart = image->segment[i].mem;
> - mend = mstart + image->segment[i].memsz;
> - if ((end > mstart) && (start < mend))
> + mend = mstart + image->segment[i].memsz - 1;
> + if ((end >= mstart) && (start <= mend))
> return 1;
> }
>
> @@ -372,7 +372,7 @@ static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
> addr = pfn << PAGE_SHIFT;
> eaddr = epfn << PAGE_SHIFT;
eaddr = epfn << PAGE_SHIFT - 1;
The overall looks good to me, one tiny concern is I would like to
have 'eaddr' changed as above if a specific local variable has been
defined.
> if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||
> - kimage_is_destination_range(image, addr, eaddr)) {
> + kimage_is_destination_range(image, addr, eaddr - 1)) {
Then we have:
+ kimage_is_destination_range(image, addr, eaddr)) {
> list_add(&pages->lru, &extra_pages);
> pages = NULL;
> }
> @@ -716,7 +716,7 @@ static struct page *kimage_alloc_page(struct kimage *image,
>
> /* If the page is not a destination page use it */
> if (!kimage_is_destination_range(image, addr,
> - addr + PAGE_SIZE))
> + addr + PAGE_SIZE - 1))
> break;
>
> /*
> --
> 2.43.0
>
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