Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 25 Mar 2019 16:44:40 -0700
From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        syzbot <syzbot+7a8ba368b47fdefca61e@syzkaller.appspotmail.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: KASAN: use-after-free Read in path_lookupat
Message-ID: <20190325234439.jimxj6q4bs5ndrwf@ast-mbp>
References: <0000000000006946d2057bbd0eef@google.com>
 <CAHk-=wiijJMTw=nTj_ED+YWMCrvHzh3ezfVYRxvzcW6+trgyPA@mail.gmail.com>
 <20190325045744.GK2217@ZenIV.linux.org.uk>
 <CAHk-=wg4iJsMHBzK52WzP+5_92HbwvX_vh_s4mMUuN0FJGdM5A@mail.gmail.com>
 <CAHk-=whJ4M5FegOLvnjUtJ0+pHv4L8UNFt+9jJDhox3Ada8kwA@mail.gmail.com>
 <20190325211405.GP2217@ZenIV.linux.org.uk>
 <CAHk-=wj+-e=X9cvvNwc5+QuvBOyYT7OtZTBzy-Wg8zGrUwxSbw@mail.gmail.com>
 <20190325233731.GS2217@ZenIV.linux.org.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190325233731.GS2217@ZenIV.linux.org.uk>
User-Agent: NeoMutt/20180223
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Mar 25, 2019 at 11:37:32PM +0000, Al Viro wrote:
> 
> For debugfs it's clearly "use default ->evict_inode(), have explicit
> ->destroy_inode() using free_inode_nonrcu()" - there we have nothing
> else done in ->evict_inode() and kfree is obviously safe in softirq.
> I'll post that (or push to vfs.git#fixes), along with minimal fixes
> for other 3.  If bpf_any_put() is softirq-safe, we'll have the full
> set for -stable and the rest could be done on top of that.

Yes. bpf_any_put() is safe to be called from softirq.