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xen/xenbus: ensure xenbus_map_ring_valloc() returns proper grant status 

xenbus_map_ring_valloc() maps a ring page and returns the status of the
used grant (0 meaning success).

There are Xen hypervisors which might return the value 1 for the status
of a failed grant mapping due to a bug. Some callers of
xenbus_map_ring_valloc() test for errors by testing the returned status
to be less than zero, resulting in no error detected and crashing later
due to a not available ring page.

Set the return value of xenbus_map_ring_valloc() to GNTST_general_error
in case the grant status reported by Xen is greater than zero.

This is part of XSA-316.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Wei Liu <wl@xen.org>
Link: https://lore.kernel.org/r/20200326080358.1018-1-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Juergen Gross 2020-03-26 09:03:58 +01:00
parent d6f34f4c6b
commit 6b51fd3f65
1 changed files with 8 additions and 1 deletions
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9
drivers/xen/xenbus/xenbus_client.c
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@ -448,7 +448,14 @@ EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t *gnt_refs,
unsigned int nr_grefs, void **vaddr)
{
return ring_ops->map(dev, gnt_refs, nr_grefs, vaddr);
int err;
err = ring_ops->map(dev, gnt_refs, nr_grefs, vaddr);
/* Some hypervisors are buggy and can return 1. */
if (err > 0)
err = GNTST_general_error;
return err;
}
EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);