linux-kernel - Re: [PATCH] fs/super: fix memory leak of s_fs_info on setup_bdev

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] [day] [month] [year] [list]

Message-ID: <1a2445d1-6fbb-4133-b5b7-72254e96d815@gmail.com>
Date: Fri, 14 Nov 2025 18:15:16 +0100
From: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@...il.com>
To: Christian Brauner <brauner@...nel.org>
Cc: syzbot+ad45f827c88778ff7df6@...kaller.appspotmail.com, frank.li@...o.com,
 glaubitz@...sik.fu-berlin.de, linux-fsdevel@...r.kernel.org,
 linux-kernel@...r.kernel.org, slava@...eyko.com,
 syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] fs/super: fix memory leak of s_fs_info on
 setup_bdev_super failure

On 11/14/25 12:55 PM, Christian Brauner wrote:
> On Fri, Nov 14, 2025 at 06:12:12AM +0100, Mehdi Ben Hadj Khelifa wrote:
>> #syz test
>>
>> diff --git a/fs/super.c b/fs/super.c
>> index 5bab94fb7e03..a99e5281b057 100644
>> --- a/fs/super.c
>> +++ b/fs/super.c
>> @@ -1690,6 +1690,11 @@ int get_tree_bdev_flags(struct fs_context *fc,
>>   		if (!error)
>>   			error = fill_super(s, fc);
>>   		if (error) {
>> +			/*
>> +			 * return back sb_info ownership to fc to be freed by put_fs_context()
>> +			 */
>> +			fc->s_fs_info = s->s_fs_info;
>> +			s->s_fs_info = NULL;
>>   			deactivate_locked_super(s);
>>   			return error;
>>   		}
>> -- 
>> 2.51.2
>>
> 
> No, either free it in hfs_fill_super() when it fails or add a wrapper
> around kill_block_super() for hfs and free it after ->kill_sb() has run.

Sorry for the noise,Resending with proper CCs:

I forgot to mention. I was giving back the ownership to the filesystem 
context because upon setup_bdev_super fails put_fs_context still gets 
called even if I would free s_fs_info in the kill_sb,so hfs_free_fc 
would get a NULL pointer to kfree as a result..I don't think that would 
be desirable.

I would be sending my patch out for more discussion.

Best Regards,
Mehdi Ben Hadj Khelifa