From: Jann Horn jannh@google.com
commit 0fcc4c8c044e117ac126ab6df4138ea9a67fa2a9 upstream.
When dev_exception_add() returns an error (due to a failed memory allocation), make sure that we move the RCU preemption count back to where it was before we were called. We dropped the RCU read lock inside the loop body, so we can't just "break".
sparse complains about this, too:
$ make -s C=2 security/device_cgroup.o ./include/linux/rcupdate.h:647:9: warning: context imbalance in 'propagate_exception' - unexpected unlock
Fixes: d591fb56618f ("device_cgroup: simplify cgroup tree walk in propagate_exception()") Cc: stable@vger.kernel.org Signed-off-by: Jann Horn jannh@google.com Acked-by: Michal Hocko mhocko@suse.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- security/device_cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -569,7 +569,7 @@ static int propagate_exception(struct de devcg->behavior == DEVCG_DEFAULT_ALLOW) { rc = dev_exception_add(devcg, ex); if (rc) - break; + return rc; } else { /* * in the other possible cases: