Re: [Patch v2] btrfs: use file_remove_suid() after i_mutex is held

[Amerigo Wang]

Tao Ma wrote:
> Hi Amerigo,
>
> Amerigo Wang wrote:
> > V1 -> V2:
> > Move kmalloc() before mutex_lock(), suggested by Arjan.
> >
> > file_remove_suid() should be called with i_mutex held,
> > file_update_time() too. So move them after mutex_lock().
> >
> > Plus, check the return value of kmalloc().
> >
> > Signed-off-by: WANG Cong <amwang@xxxxxxxxxx>
> > Cc: Arjan <arjan@xxxxxxxxxxxxx>
> > Cc: Chris Mason <chris.mason@xxxxxxxxxx>
> > Cc: Yan Zheng <zheng.yan@xxxxxxxxxx>
> > Cc: Sven Wegener <sven.wegener@xxxxxxxxxxx>
> > Cc: Josef Bacik <jbacik@xxxxxxxxxx>
> > Cc: Jeff Mahoney <jeffm@xxxxxxxx>
> >
> > ---
> > diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> > index 7c3cd24..09ef5d6 100644
> > --- a/fs/btrfs/file.c
> > +++ b/fs/btrfs/file.c
> > @@ -944,14 +944,17 @@ static ssize_t btrfs_file_write(struct file 
> > *file, const char __user *buf,
> >      if (count == 0)
> >          goto out_nolock;
> >  
> > +    pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
> > +    if (!pages)
> > +        goto out_nolock;
> I guess you need to set err to -ENOMEM here so that the caller knows 
> what's wrong. With your patch, this function just return 0(since 
> num_written and err are both 0) with no error, and I guess it is worse 
> than kernel BUG out when the NULL pages is used later.

Agree. Thanks, I will update it.

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