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Ethan Barnes authored
If cpuhp_store_callbacks() is called for CPUHP_AP_ONLINE_DYN or CPUHP_BP_PREPARE_DYN, which are the indicators for dynamically allocated states, then cpuhp_store_callbacks() allocates a new dynamic state. The first allocation in each range returns CPUHP_AP_ONLINE_DYN or CPUHP_BP_PREPARE_DYN. If cpuhp_remove_state() is invoked for one of these states, then there is no protection against the allocation mechanism. So the removal, which should clear the callbacks and the name, gets a new state assigned and clears that one. As a consequence the state which should be cleared stays initialized. A consecutive CPU hotplug operation dereferences the state callbacks and accesses either freed or reused memory, resulting in crashes. Add a protection against this by checking the name argument for NULL. If it's NULL it's a removal. If not, it's an allocation. [ tglx: Added a comment and massaged changelog ] Fixes: 5b7aa87e ("cpu/hotplug: Implement setup/removal interface") Signed-off-by:
Ethan Barnes <ethan.barnes@sandisk.com> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.or> Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu> Cc: Sebastian Siewior <bigeasy@linutronix.d> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/DM2PR04MB398242FC7776D603D9F99C894A60@DM2PR04MB398.namprd04.prod.outlook.com
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