Re: [RFC PATCH v4 5/5] btrfs: ioctl: don't free iov when -EAGAIN in uring encoded read

[Sidong Yang <sidong.yang@furiosa.ai>]

On Tue, Mar 18, 2025 at 07:21:00AM +0000, Pavel Begunkov wrote:
> On 3/17/25 13:57, Sidong Yang wrote:
> > This patch fixes a bug on encoded_read. In btrfs_uring_encoded_read(),
> > btrfs_encoded_read could return -EAGAIN when receiving requests concurrently.
> > And data->iov goes to out_free and it freed and return -EAGAIN. io-uring
> > subsystem would call it again and it doesn't reset data. And data->iov
> > freed and iov_iter reference it. iov_iter would be used in
> > btrfs_uring_read_finished() and could be raise memory bug.
> 
> Fixes should go first. Please send it separately, and CC Mark.
> A "Fixes" tag would also be good to have.

Okay, I'll remove this from patch series.

Thanks,
Sidong

> 
> > Signed-off-by: Sidong Yang <sidong.yang@furiosa.ai>
> > ---
> >   fs/btrfs/ioctl.c | 3 +++
> >   1 file changed, 3 insertions(+)
> > 
> > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> > index a7b52fd99059..02fa8dd1a3ce 100644
> > --- a/fs/btrfs/ioctl.c
> > +++ b/fs/btrfs/ioctl.c
> > @@ -4922,6 +4922,9 @@ static int btrfs_uring_encoded_read(struct io_uring_cmd *cmd, unsigned int issue
> >   	ret = btrfs_encoded_read(&kiocb, &data->iter, &data->args, &cached_state,
> >   				 &disk_bytenr, &disk_io_size);
> > +
> > +	if (ret == -EAGAIN)
> > +		goto out_acct;
> >   	if (ret < 0 && ret != -EIOCBQUEUED)
> >   		goto out_free;
> 
> -- 
> Pavel Begunkov
>