[ Upstream commit ec9c7d19336ee98ecba8de80128aa405c45feebb ]
Exercising CPU hotplug on a 5.2 kernel with recent padata fixes from cryptodev-2.6.git in an 8-CPU kvm guest...
# modprobe tcrypt alg="pcrypt(rfc4106(gcm(aes)))" type=3 # echo 0 > /sys/devices/system/cpu/cpu1/online # echo c > /sys/kernel/pcrypt/pencrypt/parallel_cpumask # modprobe tcrypt mode=215
...caused the following crash:
BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 2 PID: 134 Comm: kworker/2:2 Not tainted 5.2.0-padata-base+ #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-<snip> Workqueue: pencrypt padata_parallel_worker RIP: 0010:padata_reorder+0xcb/0x180 ... Call Trace: padata_do_serial+0x57/0x60 pcrypt_aead_enc+0x3a/0x50 [pcrypt] padata_parallel_worker+0x9b/0xe0 process_one_work+0x1b5/0x3f0 worker_thread+0x4a/0x3c0 ...
In padata_alloc_pd, pd->cpu is set using the user-supplied cpumask instead of the effective cpumask, and in this case cpumask_first picked an offline CPU.
The offline CPU's reorder->list.next is NULL in padata_reorder because the list wasn't initialized in padata_init_pqueues, which only operates on CPUs in the effective mask.
Fix by using the effective mask in padata_alloc_pd.
Fixes: 6fc4dbcf0276 ("padata: Replace delayed timer with immediate workqueue in padata_reorder") 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 Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Daniel Jordan daniel.m.jordan@oracle.com --- kernel/padata.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/padata.c b/kernel/padata.c index 66d96ed62286..6d0cdee9d321 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -450,7 +450,7 @@ static struct parallel_data *padata_alloc_pd(struct padata_instance *pinst, atomic_set(&pd->refcnt, 1); pd->pinst = pinst; spin_lock_init(&pd->lock); - pd->cpu = cpumask_first(pcpumask); + pd->cpu = cpumask_first(pd->cpumask.pcpu); INIT_WORK(&pd->reorder_work, invoke_padata_reorder);
return pd;