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device_cgroup: fix RCU imbalance in error case 

commit 0fcc4c8c04 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: d591fb5661 ("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>
This commit is contained in:
Jann Horn 2019-03-19 02:36:59 +01:00 committed by Greg Kroah-Hartman
parent d069fe4844
commit 80ef021be1
1 changed files with 1 additions and 1 deletions
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2
security/device_cgroup.c
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@ -569,7 +569,7 @@ static int propagate_exception(struct dev_cgroup *devcg_root,
devcg->behavior == DEVCG_DEFAULT_ALLOW) {
rc = dev_exception_add(devcg, ex);
if (rc)
break;
return rc;
} else {
/*
* in the other possible cases: