* [PATCH v3] mtd: ubi: fix possible null-ptr-deref in ubi_free_volume()
@ 2022-11-14 10:26 Yang Yingliang
2022-11-14 12:19 ` Zhihao Cheng
0 siblings, 1 reply; 2+ messages in thread
From: Yang Yingliang @ 2022-11-14 10:26 UTC (permalink / raw)
To: linux-mtd; +Cc: richard, miquel.raynal, vigneshr, yangyingliang, chengzhihao1
It willl cause null-ptr-deref in the following case:
uif_init()
ubi_add_volume()
cdev_add() -> if it fails, call kill_volumes()
device_register()
kill_volumes() -> if ubi_add_volume() fails call this function
ubi_free_volume()
cdev_del()
device_unregister() -> trying to delete a not added device,
it causes null-ptr-deref
So in ubi_free_volume(), it delete devices whether they are added
or not, it will causes null-ptr-deref.
Handle the error case whlie calling ubi_add_volume() to fix this
problem. If add volume fails, set the corresponding vol to null,
so it can not be accessed in kill_volumes() and release the
resource in ubi_add_volume() error path.
Fixes: 801c135ce73d ("UBI: Unsorted Block Images")
Suggested-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
v2 -> v3:
Handle the error case whlie calling ubi_add_volume().
v1 -> v2:
Replace kfree() with vol_release() to avoid memory leak, if device is not initalized.
---
drivers/mtd/ubi/build.c | 1 +
drivers/mtd/ubi/vmt.c | 12 ++++++------
2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index a901f8edfa41..4990c99eeb56 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -468,6 +468,7 @@ static int uif_init(struct ubi_device *ubi)
err = ubi_add_volume(ubi, ubi->volumes[i]);
if (err) {
ubi_err(ubi, "cannot add volume %d", i);
+ ubi->volumes[i] = NULL;
goto out_volumes;
}
}
diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 8fcc0bdf0635..c663ad14c503 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -580,6 +580,7 @@ int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
if (err) {
ubi_err(ubi, "cannot add character device for volume %d, error %d",
vol_id, err);
+ vol_release(&vol->dev);
return err;
}
@@ -590,15 +591,14 @@ int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
vol->dev.groups = volume_dev_groups;
dev_set_name(&vol->dev, "%s_%d", ubi->ubi_name, vol->vol_id);
err = device_register(&vol->dev);
- if (err)
- goto out_cdev;
+ if (err) {
+ cdev_del(&vol->cdev);
+ put_device(&vol->dev);
+ return err;
+ }
self_check_volumes(ubi);
return err;
-
-out_cdev:
- cdev_del(&vol->cdev);
- return err;
}
/**
--
2.25.1
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http://lists.infradead.org/mailman/listinfo/linux-mtd/
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v3] mtd: ubi: fix possible null-ptr-deref in ubi_free_volume()
2022-11-14 10:26 [PATCH v3] mtd: ubi: fix possible null-ptr-deref in ubi_free_volume() Yang Yingliang
@ 2022-11-14 12:19 ` Zhihao Cheng
0 siblings, 0 replies; 2+ messages in thread
From: Zhihao Cheng @ 2022-11-14 12:19 UTC (permalink / raw)
To: Yang Yingliang, linux-mtd; +Cc: richard, miquel.raynal, vigneshr
在 2022/11/14 18:26, Yang Yingliang 写道:
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
> It willl cause null-ptr-deref in the following case:
>
> uif_init()
> ubi_add_volume()
> cdev_add() -> if it fails, call kill_volumes()
> device_register()
>
> kill_volumes() -> if ubi_add_volume() fails call this function
> ubi_free_volume()
> cdev_del()
> device_unregister() -> trying to delete a not added device,
> it causes null-ptr-deref
>
> So in ubi_free_volume(), it delete devices whether they are added
> or not, it will causes null-ptr-deref.
>
> Handle the error case whlie calling ubi_add_volume() to fix this
> problem. If add volume fails, set the corresponding vol to null,
> so it can not be accessed in kill_volumes() and release the
> resource in ubi_add_volume() error path.
>
> Fixes: 801c135ce73d ("UBI: Unsorted Block Images")
> Suggested-by: Zhihao Cheng <chengzhihao1@huawei.com>
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> ---
> v2 -> v3:
> Handle the error case whlie calling ubi_add_volume().
>
> v1 -> v2:
> Replace kfree() with vol_release() to avoid memory leak, if device is not initalized.
> ---
> drivers/mtd/ubi/build.c | 1 +
> drivers/mtd/ubi/vmt.c | 12 ++++++------
> 2 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
> index a901f8edfa41..4990c99eeb56 100644
> --- a/drivers/mtd/ubi/build.c
> +++ b/drivers/mtd/ubi/build.c
> @@ -468,6 +468,7 @@ static int uif_init(struct ubi_device *ubi)
> err = ubi_add_volume(ubi, ubi->volumes[i]);
> if (err) {
> ubi_err(ubi, "cannot add volume %d", i);
> + ubi->volumes[i] = NULL;
> goto out_volumes;
> }
> }
> diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
> index 8fcc0bdf0635..c663ad14c503 100644
> --- a/drivers/mtd/ubi/vmt.c
> +++ b/drivers/mtd/ubi/vmt.c
> @@ -580,6 +580,7 @@ int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
> if (err) {
> ubi_err(ubi, "cannot add character device for volume %d, error %d",
> vol_id, err);
> + vol_release(&vol->dev);
> return err;
> }
>
> @@ -590,15 +591,14 @@ int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
> vol->dev.groups = volume_dev_groups;
> dev_set_name(&vol->dev, "%s_%d", ubi->ubi_name, vol->vol_id);
> err = device_register(&vol->dev);
> - if (err)
> - goto out_cdev;
> + if (err) {
> + cdev_del(&vol->cdev);
> + put_device(&vol->dev);
> + return err;
> + }
>
> self_check_volumes(ubi);
> return err;
> -
> -out_cdev:
> - cdev_del(&vol->cdev);
> - return err;
> }
>
> /**
>
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http://lists.infradead.org/mailman/listinfo/linux-mtd/
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