2019-09-26 00:36:01

by Navid Emamdoost

Subject: [PATCH] btrfs: prevent memory leak

In btrfsic_mount if btrfsic_dev_state_alloc fails the allocated state
will be leaked. It needs to be released on error handling path.

Signed-off-by: Navid Emamdoost <[email protected]>
---
fs/btrfs/check-integrity.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
index 0b52ab4cb964..8a77b0cb2db3 100644
--- a/fs/btrfs/check-integrity.c
+++ b/fs/btrfs/check-integrity.c
@@ -2941,6 +2941,7 @@ int btrfsic_mount(struct btrfs_fs_info *fs_info,
if (NULL == ds) {
pr_info("btrfs check-integrity: kmalloc() failed!\n");
mutex_unlock(&btrfsic_mutex);
+ kvfree(state);
return -ENOMEM;
}
ds->bdev = device->bdev;
--
2.17.1

2019-09-26 00:44:09

by Nikolay Borisov

Subject: Re: [PATCH] btrfs: prevent memory leak

On 24.09.19 г. 1:34 ч., Navid Emamdoost wrote:
> In btrfsic_mount if btrfsic_dev_state_alloc fails the allocated state
> will be leaked. It needs to be released on error handling path.
>
> Signed-off-by: Navid Emamdoost <[email protected]>

NAK.

The allocated state could have been added to a btrfsic_dev_state which
in turn is linked by btrfsic_dev_state_hashtable_add. So when later
ds->state is dereferenced it will case a UAF and likely result in crash.

Looking at the integrity code I also don't like how it's structured e.g.
if a memory error occurs then only some devices will be added to the
btrfsic_dev_State_hashtable and the super block is not going to be
validated at all.

> ---
> fs/btrfs/check-integrity.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
> index 0b52ab4cb964..8a77b0cb2db3 100644
> --- a/fs/btrfs/check-integrity.c
> +++ b/fs/btrfs/check-integrity.c
> @@ -2941,6 +2941,7 @@ int btrfsic_mount(struct btrfs_fs_info *fs_info,
> if (NULL == ds) {
> pr_info("btrfs check-integrity: kmalloc() failed!\n");
> mutex_unlock(&btrfsic_mutex);
> + kvfree(state);
> return -ENOMEM;
> }
> ds->bdev = device->bdev;
>