Re: [PATCH] btrfs: qgroup: fix memory leak when add_qgroup_item() fails

[Qu Wenruo <wqu@suse.com>]

在 2025/12/12 13:33, David Sterba 写道:
> On Fri, Dec 12, 2025 at 06:22:24AM +0530, Deepanshu Kartikey wrote:
>> If add_qgroup_item() fails, we jump to the out label without freeing the
>> preallocated qgroup structure. This causes a memory leak and triggers
>> the ASSERT(prealloc == NULL) assertion.
>>
>> Fix this by freeing prealloc and setting it to NULL before jumping to
>> the out label when add_qgroup_item() fails.
>>
>> Reported-by: syzbot+803e4cb8245b52928347@syzkaller.appspotmail.com
>> Closes: https://syzkaller.appspot.com/bug?extid=803e4cb8245b52928347
>> Fixes: 8d54518b5e52 ("btrfs: qgroup: pre-allocate btrfs_qgroup to reduce GFP_ATOMIC usage")

And that's the wrong commit, at that commit things are still correct and 
no leakage.

>> Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
> 
> Thanks for the fix, this has been fixed in a different way by commit
> https://github.com/btrfs/linux/commit/b95d1588dd2395d0fa1cd3ecf368b2dcec5445ff
> and there were more problems than the one you fixed.
> 
> You're probably using master branch where this code is still broken so
> the fix is present only in the development for-next branch. It's been in
> linux-next.git though so you may want to check there first before
> sending fixes.