> On Wed, Feb 22, 2017 at 11:20:31AM +0000, Reshetova, Elena wrote: > > > On Tue, Feb 21, 2017 at 05:49:01PM +0200, Elena Reshetova wrote: > > > > refcount_t type and corresponding API should be > > > > used instead of atomic_t when the variable is used as > > > > a reference counter. This allows to avoid accidental > > > > refcounter overflows that might lead to use-after-free > > > > situations. > > > > > > I'm missing something: how do you overflow a log item object > > > reference count? > > > > We are currently converting all reference counters present in kernel to a > safer refcount_t type. > > Yes, I see that you are taking anything that you *think* is an > object lifetime reference counter and changing it. > > > Agreed, in some cases it might be easier or harder to actually > > create/trigger > an overflow, but since it can be caused even by a bug in the legitimate code > (current version or its future iterative), it is good idea to do "safe > defaults" and > stop worrying about the problem. > > > > Do you have any reasons why it should not be converted? > > It's core dirty metadata object code. Any change to code in this > area needs to be gone over with a fine tooth comb, because bugs can > result in filesystem and/or journal corruption issues that may not > be noticed until a system crashes and log recovery fails and the > user loses their entire filesystem.... > > Hence the repeated comments about needing to actually test the code > you are changing.
Sure, we are now in the process of testing this run-time as was suggested using xfstests. I will only repost this series after we done with testing and fix issues. Best Regards, Elena. > > Cheers, > > Dave. > -- > Dave Chinner > da...@fromorbit.com
