From: Andrew Melnychenko <andrew@xxxxxxxxxx> If there is a lot(more then 16) of virtio-console devices or virtio_console module is reloaded - buffers 'vtermnos' and 'cons_ops' are overflowed. In older kernels it overruns spinlock which leads to kernel freezing: https://bugzilla.redhat.com/show_bug.cgi?id=1786239 Signed-off-by: Andrew Melnychenko <andrew@xxxxxxxxxx> --- drivers/tty/hvc/hvc_console.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index 27284a2dcd2b..436cc51c92c3 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -302,10 +302,6 @@ int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops) vtermnos[index] = vtermno; cons_ops[index] = ops; - /* reserve all indices up to and including this index */ - if (last_hvc < index) - last_hvc = index; - /* check if we need to re-register the kernel console */ hvc_check_console(index); @@ -960,13 +956,22 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data, cons_ops[i] == hp->ops) break; - /* no matching slot, just use a counter */ - if (i >= MAX_NR_HVC_CONSOLES) - i = ++last_hvc; + if (i >= MAX_NR_HVC_CONSOLES) { + + /* find 'empty' slot for console */ + for (i = 0; i < MAX_NR_HVC_CONSOLES && vtermnos[i] != -1; i++) { + } + + /* no matching slot, just use a counter */ + if (i == MAX_NR_HVC_CONSOLES) + i = ++last_hvc + MAX_NR_HVC_CONSOLES; + } hp->index = i; - cons_ops[i] = ops; - vtermnos[i] = vtermno; + if (i < MAX_NR_HVC_CONSOLES) { + cons_ops[i] = ops; + vtermnos[i] = vtermno; + } list_add_tail(&(hp->next), &hvc_structs); mutex_unlock(&hvc_structs_mutex); -- 2.24.1 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
