linux-kernel - Re: [syzbot] [bcachefs?] KASAN: slab-use-after-free Read in bch2_reconstruct

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f5eb3203-62c1-4bdd-9607-122f13eacf70@gmx.com>
Date: Fri, 25 Oct 2024 15:14:24 +1030
From: Qu Wenruo <quwenruo.btrfs@....com>
To: Lizhi Xu <lizhi.xu@...driver.com>
Cc: clm@...com, dsterba@...e.com, josef@...icpanda.com,
 linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
 syzbot+3030e17bd57a73d39bd7@...kaller.appspotmail.com,
 syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bcachefs?] KASAN: slab-use-after-free Read in
 bch2_reconstruct_alloc



在 2024/10/25 15:08, Lizhi Xu 写道:
> On Fri, 25 Oct 2024 14:49:48 +1030, Qu Wenruo wrote:
>>> use the input logical can't find the extent root, so add sanity check for
>>> extent root before search slot.
>>>
>>> #syz test
>>>
>>> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
>>> index f8e1d5b2c512..87eaf5dd2d5d 100644
>>> --- a/fs/btrfs/backref.c
>>> +++ b/fs/btrfs/backref.c
>>> @@ -2213,6 +2213,9 @@ int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
>>>        key.objectid = logical;
>>>        key.offset = (u64)-1;
>>>
>>> +     if (!extent_root)
>>> +             return -ENOENT;
>>
>> Considering we have a lot of such btrfs_search_slot() without checking
>> if the csum/extent root is NULL, can we move the check into
>> btrfs_search_slot()?
> Yes, judging in btrfs_search_slot can fix the current issue while also
> avoiding similar problems.
>

Can't wait for your formal fix on this.

Thanks,
Qu

> #syz test
>
> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
> index 0cc919d15b14..9c05cab473f5 100644
> --- a/fs/btrfs/ctree.c
> +++ b/fs/btrfs/ctree.c
> @@ -2010,7 +2010,7 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
>   		      const struct btrfs_key *key, struct btrfs_path *p,
>   		      int ins_len, int cow)
>   {
> -	struct btrfs_fs_info *fs_info = root->fs_info;
> +	struct btrfs_fs_info *fs_info;
>   	struct extent_buffer *b;
>   	int slot;
>   	int ret;
> @@ -2023,6 +2023,10 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
>   	int min_write_lock_level;
>   	int prev_cmp;
>
> +	if (!root)
> +		return -EINVAL;
> +
> +	fs_info = root->fs_info;
>   	might_sleep();
>
>   	lowest_level = p->lowest_level;