Messages in this thread | | | Date | Tue, 15 Sep 2009 21:32:04 +0200 | From | Jens Axboe <> | Subject | Re: [patch 3/5] fs: fix bdi writeback use after free 1 |
| |
On Wed, Sep 16 2009, npiggin@suse.de wrote: > By the time bdi_work_on_stack gets evaluated again in bdi_work_free, it > cna already have been deallocated and used for something else in the > !on stack case, giving a false positive in this test and causing corruption.
You are right, that is also buggy... Applied.
> > Signed-off-by: Nick Piggin <npiggin@suse.de> > --- > fs/fs-writeback.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > Index: linux-2.6/fs/fs-writeback.c > =================================================================== > --- linux-2.6.orig/fs/fs-writeback.c > +++ linux-2.6/fs/fs-writeback.c > @@ -114,6 +114,7 @@ static void bdi_work_free(struct rcu_hea > static void wb_work_complete(struct bdi_work *work) > { > const enum writeback_sync_modes sync_mode = work->sync_mode; > + int onstack = bdi_work_on_stack(work); > > /* > * For allocated work, we can clear the done/seen bit right here. > @@ -121,9 +122,9 @@ static void wb_work_complete(struct bdi_ > * to after the RCU grace period, since the stack could be invalidated > * as soon as bdi_work_clear() has done the wakeup. > */ > - if (!bdi_work_on_stack(work)) > + if (!onstack) > bdi_work_clear(work); > - if (sync_mode == WB_SYNC_NONE || bdi_work_on_stack(work)) > + if (sync_mode == WB_SYNC_NONE || onstack) > call_rcu(&work->rcu_head, bdi_work_free); > } > > >
-- Jens Axboe
| |