On Fri, Mar 03, 2017 at 10:55:09AM +0200, Elena Reshetova wrote: > Now when new refcount_t type and API are finally merged > (see include/linux/refcount.h), the following > patches convert various refcounters in the btrfs filesystem from atomic_t > to refcount_t. By doing this we prevent intentional or accidental > underflows or overflows that can led to use-after-free vulnerabilities. > > The below patches are fully independent and can be cherry-picked separately. > Since we convert all kernel subsystems in the same fashion, resulting > in about 300 patches, we have to group them for sending at least in some > fashion to be manageable. Please excuse the long cc list. Thanks, the patchset looks good to me, I'm going to add it to the 4.12 queue. > These patches have been tested with xfstests by running btrfs-related tests. > btrfs debug was enabled, warns on refcount errors, too. No output related to > refcount errors produced. However, the following errors were during the run: > * tests btrfs/078, btrfs/114, btrfs/115, no errors anywhere in dmesg, but > process hangs. They all seem to be around qgroup, sometimes error visible > such as qgroup scan failed -4 before it blocks, but not always. > * test btrfs/104 dmesg has additional error output: > BTRFS warning (device vdc): qgroup 258 reserved space underflow, have: 0, > to free: 4096 > I tried looking at the code on what causes the failure, but could not figure > it out. It doesn't seem to be related to any refcount changes at least IMO. > > The above test failures are hard for me to understand and interpreted, but > they don't seem to relate to refcount conversions. I don't think they're related to the refcount updates so we'll address them.
