ubi: block: Fix a possible use-after-free bug in ubiblock_create()

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

Posted by Harshit Mogalapalli 2 years, 6 months ago

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 <harshit.m.mogalapalli@oracle.com>
---
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

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

Posted by Christoph Hellwig 2 years, 6 months ago

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 <harshit.m.mogalapalli@oracle.com>

Thanks, this looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

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

Posted by Richard Weinberger 2 years, 6 months ago

----- Ursprüngliche Mail -----
> Von: "harshit m mogalapalli" <harshit.m.mogalapalli@oracle.com>
> 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 <harshit.m.mogalapalli@oracle.com>
> ---
> 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