On Tue, 16 Nov 2021 at 04:01, Dave Chinner <david@xxxxxxxxxxxxx> wrote: > I *think* that just zeroing the buffer means the race condition > means the link resolves as either wholly intact, partially zeroed > with trailing zeros in the length, wholly zeroed or zero length. > Nothing will crash, the link string is always null terminated even > if the length is wrong, and so nothing bad should happen as a result > of zeroing the symlink buffer when it gets evicted from the VFS > inode cache after unlink. That's my thinking. However, modifying the buffer while it is being processed does seem pretty ugly, and I have to admit that I don't understand why this needs to be done in either XFS or EXT4. > The root cause is "allowing an inode to be reused without waiting > for an RCU grace period to expire". This might seem pedantic, but > "without waiting for an rcu grace period to expire" is the important > part of the problem (i.e. the bug), not the "allowing an inode to be > reused" bit. Yes. Thanks, Miklos
