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padata: add separate cpuhp node for CPUHP_PADATA_DEAD

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Removing the pcrypt module triggers this:

  general protection fault, probably for non-canonical
    address 0xdead000000000122
  CPU: 5 PID: 264 Comm: modprobe Not tainted 5.6.0+ #2
  Hardware name: QEMU Standard PC
  RIP: 0010:__cpuhp_state_remove_instance+0xcc/0x120
  Call Trace:
   padata_sysfs_release+0x74/0xce
   kobject_put+0x81/0xd0
   padata_free+0x12/0x20
   pcrypt_exit+0x43/0x8ee [pcrypt]

padata instances wrongly use the same hlist node for the online and dead
states, so __padata_free()'s second cpuhp remove call chokes on the node
that the first poisoned.

cpuhp multi-instance callbacks only walk forward in cpuhp_step->list and
the same node is linked in both the online and dead lists, so the list
corruption that results from padata_alloc() adding the node to a second
list without removing it from the first doesn't cause problems as long
as no instances are freed.

Avoid the issue by giving each state its own node.

Fixes: 894c9ef978 ("padata: validate cpumask without removed CPU during offline")
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Daniel Jordan 2020-04-21 12:34:55 -04:00 committed by Herbert Xu
parent b2d7e8bcaa
commit 3c2214b602
2 changed files with 12 additions and 8 deletions
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6
include/linux/padata.h
View File

@ -139,7 +139,8 @@ struct padata_shell {
/**
* struct padata_instance - The overall control structure.
*
* @node: Used by CPU hotplug.
* @cpu_online_node: Linkage for CPU online callback.
* @cpu_dead_node: Linkage for CPU offline callback.
* @parallel_wq: The workqueue used for parallel work.
* @serial_wq: The workqueue used for serial work.
* @pslist: List of padata_shell objects attached to this instance.
@ -150,7 +151,8 @@ struct padata_shell {
* @flags: padata flags.
*/
struct padata_instance {
struct hlist_node node;
struct hlist_node cpu_online_node;
struct hlist_node cpu_dead_node;
struct workqueue_struct *parallel_wq;
struct workqueue_struct *serial_wq;
struct list_head pslist;

14
kernel/padata.c
View File

@ -703,7 +703,7 @@ static int padata_cpu_online(unsigned int cpu, struct hlist_node *node)
struct padata_instance *pinst;
int ret;
pinst = hlist_entry_safe(node, struct padata_instance, node);
pinst = hlist_entry_safe(node, struct padata_instance, cpu_online_node);
if (!pinst_has_cpu(pinst, cpu))
return 0;
@ -718,7 +718,7 @@ static int padata_cpu_dead(unsigned int cpu, struct hlist_node *node)
struct padata_instance *pinst;
int ret;
pinst = hlist_entry_safe(node, struct padata_instance, node);
pinst = hlist_entry_safe(node, struct padata_instance, cpu_dead_node);
if (!pinst_has_cpu(pinst, cpu))
return 0;
@ -734,8 +734,9 @@ static enum cpuhp_state hp_online;
static void __padata_free(struct padata_instance *pinst)
{
#ifdef CONFIG_HOTPLUG_CPU
cpuhp_state_remove_instance_nocalls(CPUHP_PADATA_DEAD, &pinst->node);
cpuhp_state_remove_instance_nocalls(hp_online, &pinst->node);
cpuhp_state_remove_instance_nocalls(CPUHP_PADATA_DEAD,
&pinst->cpu_dead_node);
cpuhp_state_remove_instance_nocalls(hp_online, &pinst->cpu_online_node);
#endif
WARN_ON(!list_empty(&pinst->pslist));
@ -939,9 +940,10 @@ static struct padata_instance *padata_alloc(const char *name,
mutex_init(&pinst->lock);
#ifdef CONFIG_HOTPLUG_CPU
cpuhp_state_add_instance_nocalls_cpuslocked(hp_online, &pinst->node);
cpuhp_state_add_instance_nocalls_cpuslocked(hp_online,
&pinst->cpu_online_node);
cpuhp_state_add_instance_nocalls_cpuslocked(CPUHP_PADATA_DEAD,
&pinst->node);
&pinst->cpu_dead_node);
#endif
put_online_cpus();