From: Juergen Gross jgross@suse.com
[ Upstream commit 6b51fd3f65a22e3d1471b18a1d56247e246edd46 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/xen/xenbus/xenbus_client.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c index e17ca81561713..a38292ef79f6d 100644 --- a/drivers/xen/xenbus/xenbus_client.c +++ b/drivers/xen/xenbus/xenbus_client.c @@ -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);