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firewire: prevent userspace from accessing shut down devices

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If userspace ignores the POLLERR bit from poll(), and only attempts to
read() the device when POLLIN is set, it can still make ioctl() calls on
a device that has been removed from the system.  The node_id and
generation returned by GET_INFO will be outdated, but INITIATE_BUS_RESET
would still cause a bus reset, and GET_CYCLE_TIMER will return data.
And if you guess the correct generation to use, you can send requests to
a different device on the bus, and get responses back.

This patch prevents open, ioctl, compat_ioctl, and mmap against shutdown
devices.

Signed-off-by: Jay Fenlason <fenlason@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Jay Fenlason 2008-05-16 11:15:23 -04:00 committed by Stefan Richter
parent 93c596f7d6
commit 551f4cb9de
1 changed files with 14 additions and 0 deletions
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14
drivers/firewire/fw-cdev.c
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@ -113,6 +113,11 @@ static int fw_device_op_open(struct inode *inode, struct file *file)
if (device == NULL)
return -ENODEV;
if (fw_device_is_shutdown(device)) {
fw_device_put(device);
return -ENODEV;
}
client = kzalloc(sizeof(*client), GFP_KERNEL);
if (client == NULL) {
fw_device_put(device);
@ -901,6 +906,9 @@ fw_device_op_ioctl(struct file *file,
{
struct client *client = file->private_data;
if (fw_device_is_shutdown(client->device))
return -ENODEV;
return dispatch_ioctl(client, cmd, (void __user *) arg);
}
@ -911,6 +919,9 @@ fw_device_op_compat_ioctl(struct file *file,
{
struct client *client = file->private_data;
if (fw_device_is_shutdown(client->device))
return -ENODEV;
return dispatch_ioctl(client, cmd, compat_ptr(arg));
}
#endif
@ -922,6 +933,9 @@ static int fw_device_op_mmap(struct file *file, struct vm_area_struct *vma)
unsigned long size;
int page_count, retval;
if (fw_device_is_shutdown(client->device))
return -ENODEV;
/* FIXME: We could support multiple buffers, but we don't. */
if (client->buffer.pages != NULL)
return -EBUSY;