Messages in this thread | | | Date | Tue, 19 Jan 2021 11:52:37 -0500 | From | Johannes Weiner <> | Subject | Re: [PATCH v2 1/2] cgroup: fix psi monitor for root cgroup |
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On Sat, Jan 16, 2021 at 06:36:33PM +0100, Odin Ugedal wrote: > Fix NULL pointer dereference when adding new psi monitor to the root > cgroup. PSI files for root cgroup was introduced in df5ba5be742 by using > system wide psi struct when reading, but file write/monitor was not > properly fixed. Since the PSI config for the root cgroup isn't > initialized, the current implementation tries to lock a NULL ptr, > resulting in a crash. > > Can be triggered by running this as root: > $ tee /sys/fs/cgroup/cpu.pressure <<< "some 10000 1000000" > > Signed-off-by: Odin Ugedal <odin@uged.al> > Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Fixes: df5ba5be7425 ("kernel/sched/psi.c: expose pressure metrics on root cgroup") Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Since this is a userspace-triggerable NULL ptr crash, we should probably also
Cc: stable@vger.kernel.org # 5.2+
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