Ian Campbell
2012-Jan-04 09:29 UTC
[PATCH] xen/xenbus: Reject replies with payload > XENSTORE_PAYLOAD_MAX.
This also avoids a potential integer overflow pointed out by Haogang Chen.
Signed-off-by: Ian Campbell <ian.campbell at citrix.com>
Cc: Haogang Chen <haogangchen at gmail.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Cc: Jeremy Fitzhardinge <jeremy at goop.org>
Cc: xen-devel at lists.xensource.com
Cc: virtualization at lists.linux-foundation.org
Cc: linux-kernel at vger.kernel.org
---
drivers/xen/xenbus/xenbus_xs.c | 6 ++++++
include/xen/interface/io/xs_wire.h | 3 +++
2 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index b3b8f2f..6f0121e 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -810,6 +810,12 @@ static int process_msg(void)
goto out;
}
+ if (msg->hdr.len > XENSTORE_PAYLOAD_MAX) {
+ kfree(msg);
+ err = -EINVAL;
+ goto out;
+ }
+
body = kmalloc(msg->hdr.len + 1, GFP_NOIO | __GFP_HIGH);
if (body == NULL) {
kfree(msg);
diff --git a/include/xen/interface/io/xs_wire.h
b/include/xen/interface/io/xs_wire.h
index f0b6890..3c1877c 100644
--- a/include/xen/interface/io/xs_wire.h
+++ b/include/xen/interface/io/xs_wire.h
@@ -88,4 +88,7 @@ struct xenstore_domain_interface {
XENSTORE_RING_IDX rsp_cons, rsp_prod;
};
+/* Violating this is very bad. See docs/misc/xenstore.txt. */
+#define XENSTORE_PAYLOAD_MAX 4096
+
#endif /* _XS_WIRE_H */
--
1.7.2.5