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rbd: call rbd_dev_unprobe() after unwatching and flushing notifies 

rbd_dev_unprobe() is supposed to undo most of rbd_dev_image_probe(),
including rbd_dev_header_info(), which means that rbd_dev_header_info()
isn't supposed to be called after rbd_dev_unprobe().

However, rbd_dev_image_release() calls rbd_dev_unprobe() before
rbd_unregister_watch().  This is racy because a header update notify
can sneak in:

  "rbd unmap" thread                   ceph-watch-notify worker

  rbd_dev_image_release()
    rbd_dev_unprobe()
      free and zero out header
                                       rbd_watch_cb()
                                         rbd_dev_refresh()
                                           rbd_dev_header_info()
                                             read in header

The same goes for "rbd map" because rbd_dev_image_probe() calls
rbd_dev_unprobe() on errors.  In both cases this results in a memory
leak.

Fixes: fd22aef8b4 ("rbd: move rbd_unregister_watch() call into rbd_dev_image_release()")
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Jason Dillaman <dillaman@redhat.com>
alistair/sensors
Ilya Dryomov 2020-03-16 15:52:54 +01:00
parent 0e4e1de5b6
commit 952c48b0ed
1 changed files with 4 additions and 4 deletions
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8
drivers/block/rbd.c
View File

@ -6898,9 +6898,10 @@ static void rbd_print_dne(struct rbd_device *rbd_dev, bool is_snap)
static void rbd_dev_image_release(struct rbd_device *rbd_dev)
{
rbd_dev_unprobe(rbd_dev);
if (rbd_dev->opts)
rbd_unregister_watch(rbd_dev);
rbd_dev_unprobe(rbd_dev);
rbd_dev->image_format = 0;
kfree(rbd_dev->spec->image_id);
rbd_dev->spec->image_id = NULL;
@ -6950,7 +6951,7 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, int depth)
if (ret) {
if (ret == -ENOENT && !need_watch)
rbd_print_dne(rbd_dev, false);
goto err_out_watch;
goto err_out_probe;
}
/*
@ -6995,12 +6996,11 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, int depth)
return 0;
err_out_probe:
rbd_dev_unprobe(rbd_dev);
err_out_watch:
if (!depth)
up_write(&rbd_dev->header_rwsem);
if (need_watch)
rbd_unregister_watch(rbd_dev);
rbd_dev_unprobe(rbd_dev);
err_out_format:
rbd_dev->image_format = 0;
kfree(rbd_dev->spec->image_id);