tree 4825c6a28771521a6eeff4e926d9b5a39ed7011a
parent 399a9feeac83c2f64138c438e41222a12dd71766
author Richard Weinberger <richard@nod.at> 1412254835 +0200
committer Richard Weinberger <richard@nod.at> 1427401464 +0100

UBI: Fastmap: Fix races in ubi_wl_get_peb()

ubi_wl_get_peb() has two problems, it reads the pool
size and usage counters without any protection.
While reading one value would be perfectly fine it reads multiple
values and compares them. This is racy and can lead to incorrect
pool handling.
Furthermore ubi_update_fastmap() is called without wl_lock held,
before incrementing the used counter it needs to be checked again.
It could happen that another thread consumed all PEBs from the
pool and the counter goes beyond ->size.

Signed-off-by: Richard Weinberger <richard@nod.at>