On Mon, May 15, 2023 at 6:49 AM <linan666@xxxxxxxxxxxxxxx> wrote:
>
> From: Li Nan <linan122@xxxxxxxxxx>
>
> If we write a large number to md/bitmap_set_bits, md_bitmap_checkpage()
> will return -EINVAL because 'page >= bitmap->pages', but the return value
> was not checked immediately in md_bitmap_get_counter() in order to set
> *blocks value and slab-out-of-bounds occurs.
>
> Move check of 'page >= bitmap->pages' to md_bitmap_get_counter() and
> return directly if true.
>
> Fixes: ef4256733506 ("md/bitmap: optimise scanning of empty bitmaps.")
> Signed-off-by: Li Nan <linan122@xxxxxxxxxx>
> Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> ---
> drivers/md/md-bitmap.c | 17 +++++++++--------
> 1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
> index 920bb68156d2..e122b19c124d 100644
> --- a/drivers/md/md-bitmap.c
> +++ b/drivers/md/md-bitmap.c
> @@ -46,6 +46,7 @@ static inline char *bmname(struct bitmap *bitmap)
> *
> * if we find our page, we increment the page's refcount so that it stays
> * allocated while we're using it
> + * the caller must make sure 'page < bimap->pages'
> */
I removed this comment, and added WARN_ON_ONCE().
Thanks,
Song
> static int md_bitmap_checkpage(struct bitmap_counts *bitmap,
> unsigned long page, int create, int no_hijack)
> @@ -54,14 +55,6 @@ __acquires(bitmap->lock)
> {
> unsigned char *mappage;
>
> - if (page >= bitmap->pages) {
> - /* This can happen if bitmap_start_sync goes beyond
> - * End-of-device while looking for a whole page.
> - * It is harmless.
> - */
> - return -EINVAL;
> - }
> -
> if (bitmap->bp[page].hijacked) /* it's hijacked, don't try to alloc */
> return 0;
>
> @@ -1387,6 +1380,14 @@ __acquires(bitmap->lock)
> sector_t csize;
> int err;
>
> + if (page >= bitmap->pages) {
> + /*
> + * This can happen if bitmap_start_sync goes beyond
> + * End-of-device while looking for a whole page or
> + * user set a huge number to sysfs bitmap_set_bits.
> + */
> + return NULL;
> + }
> err = md_bitmap_checkpage(bitmap, page, create, 0);
>
> if (bitmap->bp[page].hijacked ||
> --
> 2.31.1
>
