2023-02-14 09:38:34

by Harshit Mogalapalli

Subject: [PATCH linux-next] ubi: block: Fix a possible use-after-free bug in ubiblock_create()

Smatch warns:
drivers/mtd/ubi/block.c:438 ubiblock_create()
warn: '&dev->list' not removed from list

'dev' is freed in 'out_free_dev:, but it is still on the list.

To fix this, delete the list item before freeing.

Fixes: 91cc8fbcc8c7 ("ubi: block: set BLK_MQ_F_BLOCKING")
Signed-off-by: Harshit Mogalapalli <[email protected]>
---
Found by static analysis(smatch). Only Compile tested.
---
drivers/mtd/ubi/block.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index f5d036203fe7..763704c8d05c 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -429,6 +429,7 @@ int ubiblock_create(struct ubi_volume_info *vi)
return 0;

out_remove_minor:
+ list_del(&dev->list);
idr_remove(&ubiblock_minor_idr, gd->first_minor);
out_cleanup_disk:
put_disk(dev->gd);
--
2.38.1

2023-02-14 09:48:20

by Richard Weinberger

Subject: Re: [PATCH linux-next] ubi: block: Fix a possible use-after-free bug in ubiblock_create()

----- Ursprüngliche Mail -----
> Von: "harshit m mogalapalli" <[email protected]>
> Smatch warns:
> drivers/mtd/ubi/block.c:438 ubiblock_create()
> warn: '&dev->list' not removed from list
>
> 'dev' is freed in 'out_free_dev:, but it is still on the list.
>
> To fix this, delete the list item before freeing.
>
> Fixes: 91cc8fbcc8c7 ("ubi: block: set BLK_MQ_F_BLOCKING")
> Signed-off-by: Harshit Mogalapalli <[email protected]>
> ---
> Found by static analysis(smatch). Only Compile tested.
> ---
> drivers/mtd/ubi/block.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
> index f5d036203fe7..763704c8d05c 100644
> --- a/drivers/mtd/ubi/block.c
> +++ b/drivers/mtd/ubi/block.c
> @@ -429,6 +429,7 @@ int ubiblock_create(struct ubi_volume_info *vi)
> return 0;
>
> out_remove_minor:
> + list_del(&dev->list);
> idr_remove(&ubiblock_minor_idr, gd->first_minor);
> out_cleanup_disk:
> put_disk(dev->gd);

Good catch!

Thanks,
//richard

2023-02-14 14:17:37

by Christoph Hellwig

Subject: Re: [PATCH linux-next] ubi: block: Fix a possible use-after-free bug in ubiblock_create()

On Tue, Feb 14, 2023 at 01:38:01AM -0800, Harshit Mogalapalli wrote:
> Smatch warns:
> drivers/mtd/ubi/block.c:438 ubiblock_create()
> warn: '&dev->list' not removed from list
>
> 'dev' is freed in 'out_free_dev:, but it is still on the list.
>
> To fix this, delete the list item before freeing.
>
> Fixes: 91cc8fbcc8c7 ("ubi: block: set BLK_MQ_F_BLOCKING")
> Signed-off-by: Harshit Mogalapalli <[email protected]>

Thanks, this looks good:

Reviewed-by: Christoph Hellwig <[email protected]>