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| author | Nick Piggin <npiggin@suse.de> | 2009-09-15 21:34:51 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-09-16 15:18:52 +0200 |
| commit | 77b9d059cb3ddb8b1246d5878e81d52926550b23 (patch) | |
| tree | 6d6a894d91097aec9e589d22f48d7ec387e062d9 /fs | |
| parent | 77fad5e625e56eb31a343ae1d489979fdc61a2aa (diff) | |
| download | lwn-77b9d059cb3ddb8b1246d5878e81d52926550b23.tar.gz lwn-77b9d059cb3ddb8b1246d5878e81d52926550b23.zip | |
writeback: Fix bdi use after free in wb_work_complete()
By the time bdi_work_on_stack gets evaluated again in bdi_work_free, it
can already have been deallocated and used for something else in the
!on stack case, giving a false positive in this test and causing
corruption.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/fs-writeback.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 6bca6f8176f0..7eba7326b9b9 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -113,6 +113,7 @@ static void bdi_work_free(struct rcu_head *head) static void wb_work_complete(struct bdi_work *work) { const enum writeback_sync_modes sync_mode = work->args.sync_mode; + int onstack = bdi_work_on_stack(work); /* * For allocated work, we can clear the done/seen bit right here. @@ -120,9 +121,9 @@ static void wb_work_complete(struct bdi_work *work) * 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); } |