Revision 3fff0179e33cd7d0a688dab65700c46ad089e934 authored by Mark McLoughlin on 03 February 2009, 03:03:53 UTC, committed by Linus Torvalds on 03 February 2009, 03:17:56 UTC
The host really shouldn't be notifying us of config changes before the device status is VIRTIO_CONFIG_S_DRIVER or VIRTIO_CONFIG_S_DRIVER_OK. However, if we do happen to be interrupted while we're not attached to a driver, we really shouldn't oops. Prevent this simply by checking that device->driver is non-NULL before trying to notify the driver of config changes. Problem observed by doing a "set_link virtio.0 down" with QEMU before the net driver had been loaded. Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 720eba3
maccess.c
/*
* Access kernel memory without faulting.
*/
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/mm.h>
/**
* probe_kernel_read(): safely attempt to read from a location
* @dst: pointer to the buffer that shall take the data
* @src: address to read from
* @size: size of the data chunk
*
* Safely read from address @src to the buffer at @dst. If a kernel fault
* happens, handle that and return -EFAULT.
*/
long probe_kernel_read(void *dst, void *src, size_t size)
{
long ret;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
pagefault_disable();
ret = __copy_from_user_inatomic(dst,
(__force const void __user *)src, size);
pagefault_enable();
set_fs(old_fs);
return ret ? -EFAULT : 0;
}
EXPORT_SYMBOL_GPL(probe_kernel_read);
/**
* probe_kernel_write(): safely attempt to write to a location
* @dst: address to write to
* @src: pointer to the data that shall be written
* @size: size of the data chunk
*
* Safely write to address @dst from the buffer at @src. If a kernel fault
* happens, handle that and return -EFAULT.
*/
long probe_kernel_write(void *dst, void *src, size_t size)
{
long ret;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
pagefault_disable();
ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
pagefault_enable();
set_fs(old_fs);
return ret ? -EFAULT : 0;
}
EXPORT_SYMBOL_GPL(probe_kernel_write);
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