2023-04-27 08:57:35

by Li Nan

Subject: [PATCH 1/3] md/raid10: fix slab-out-of-bounds in md_bitmap_get_counter

From: Li Nan <[email protected]>

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.

Return directly if err is -EINVAL.

Fixes: ef4256733506 ("md/bitmap: optimise scanning of empty bitmaps.")
Signed-off-by: Li Nan <[email protected]>
---
drivers/md/md-bitmap.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 920bb68156d2..0b41ef422da7 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -1388,6 +1388,8 @@ __acquires(bitmap->lock)
int err;

err = md_bitmap_checkpage(bitmap, page, create, 0);
+ if (err == -EINVAL)
+ return NULL;

if (bitmap->bp[page].hijacked ||
bitmap->bp[page].map == NULL)
--
2.31.1

2023-04-27 10:26:11

by Yu Kuai

Subject: Re: [PATCH 1/3] md/raid10: fix slab-out-of-bounds in md_bitmap_get_counter

Hi,

?? 2023/04/27 16:56, [email protected] д??:
> From: Li Nan <[email protected]>
>
> 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.
>
> Return directly if err is -EINVAL.
>
> Fixes: ef4256733506 ("md/bitmap: optimise scanning of empty bitmaps.")
> Signed-off-by: Li Nan <[email protected]>

This patch looks good to me, feel free to add??

Reviewed-by: Yu Kuai <[email protected]>

By the way, I think it's better for bitmap_store() to return error
number if bitmap doesn't exist or setting dirty bits failed.

Thnaks,
Kuai
> ---
> drivers/md/md-bitmap.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
> index 920bb68156d2..0b41ef422da7 100644
> --- a/drivers/md/md-bitmap.c
> +++ b/drivers/md/md-bitmap.c
> @@ -1388,6 +1388,8 @@ __acquires(bitmap->lock)
> int err;
>
> err = md_bitmap_checkpage(bitmap, page, create, 0);
> + if (err == -EINVAL)
> + return NULL;
>
> if (bitmap->bp[page].hijacked ||
> bitmap->bp[page].map == NULL)
>