[PATCH 4/9] virtio_console: validate max_nr_ports before trying to use it
From: Jason Wang <jasowang@redhat.com>
Date: 2021-09-13 05:54:48
Also in:
lkml
Subsystem:
char and misc drivers, the rest, virtio console driver · Maintainers:
Arnd Bergmann, Greg Kroah-Hartman, Linus Torvalds, Amit Shah
We calculate nr_ports based on the max_nr_ports: nr_queues = use_multiport(portdev) ? (nr_ports + 1) * 2 : 2; If the device advertises a large max_nr_ports, we will end up with a integer overflow. Fixing this by validating the max_nr_ports advertised by the device in .validate() and clear the MULTIPORT is it's greater than 0x8000 (which is guaranteed be safe). Cc: Amit Shah <amit@kernel.org> Signed-off-by: Jason Wang <jasowang@redhat.com> --- drivers/char/virtio_console.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index daeed31df622..ef13763699c0 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c@@ -28,6 +28,7 @@ #include "../tty/hvc/hvc_console.h" #define is_rproc_enabled IS_ENABLED(CONFIG_REMOTEPROC) +#define VIRTCONS_MAX_PORTS 0x8000 /* * This is a global struct for storing common data for all the devices
@@ -1981,6 +1982,8 @@ static void virtcons_remove(struct virtio_device *vdev) static int virtcons_validate(struct virtio_device *vdev) { + u32 max_nr_ports; + if (is_rproc_serial(vdev)) { /* Don't test F_SIZE at all if we're rproc: not a * valid feature! */
@@ -1999,6 +2002,13 @@ static int virtcons_validate(struct virtio_device *vdev) return -EINVAL; } + if (virtio_cread_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT, + struct virtio_console_config, max_nr_ports, + &max_nr_ports) == 0) { + if (max_nr_ports == 0 || max_nr_ports > VIRTCONS_MAX_PORTS) + __virtio_clear_bit(vdev, VIRTIO_CONSOLE_F_MULTIPORT); + } + return 0; }
--
2.25.1
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