On Tue, Apr 21, 2020 at 12:34:55PM -0400, Daniel Jordan wrote:
> 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: 894c9ef9780c ("padata: validate cpumask without removed CPU during
> offline")
> Signed-off-by: Daniel Jordan <daniel.m.jor...@oracle.com>
> Cc: Herbert Xu <herb...@gondor.apana.org.au>
> Cc: Steffen Klassert <steffen.klass...@secunet.com>
> Cc: linux-cry...@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: sta...@vger.kernel.org # v5.4+
> ---
> include/linux/padata.h | 6 ++++--
> kernel/padata.c | 14 ++++++++------
> 2 files changed, 12 insertions(+), 8 deletions(-)
Patch applied. Thanks.
--
Email: Herbert Xu <herb...@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
