| Message ID | 20190319013659.86199-1-jannh@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | device_cgroup: fix RCU imbalance in error case | expand |
On Tue 19-03-19 02:36:59, Jann Horn wrote: > 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> FWIW looks good to me. Acked-by: Michal Hocko <mhocko@suse.com> Thanks > --- > Compile-tested only. > > I'm not entirely sure who's supposed to be the maintainer for this thing. > The sign-offs on the commits to this file come from Tejun, but MAINTAINERS > claims it's part of security/, so I'm just sending this to both the > security folks and the cgroup folks, you can figure out whose tree you want > to take this through. :P > If the cgroup folks feel responsible for this file, maybe you could fix up > MAINTAINERS? > > security/device_cgroup.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/security/device_cgroup.c b/security/device_cgroup.c > index cd97929fac66..dc28914fa72e 100644 > --- a/security/device_cgroup.c > +++ b/security/device_cgroup.c > @@ -560,7 +560,7 @@ 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: > -- > 2.21.0.225.g810b269d1ac-goog
On Tue, Mar 19, 2019 at 02:36:59AM +0100, Jann Horn wrote: > 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> Applied to cgroup/for-5.1-fixes. Thanks.
diff --git a/security/device_cgroup.c b/security/device_cgroup.c index cd97929fac66..dc28914fa72e 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -560,7 +560,7 @@ 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:
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> --- Compile-tested only. I'm not entirely sure who's supposed to be the maintainer for this thing. The sign-offs on the commits to this file come from Tejun, but MAINTAINERS claims it's part of security/, so I'm just sending this to both the security folks and the cgroup folks, you can figure out whose tree you want to take this through. :P If the cgroup folks feel responsible for this file, maybe you could fix up MAINTAINERS? security/device_cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)