There is a potential integer overflow in process_msg() that could result
in cross-domain attack.
body = kmalloc(msg->hdr.len + 1, GFP_NOIO | __GFP_HIGH);
When a malicious guest passes 0xffffffff in msg->hdr.len, the subsequent
call to xb_read() would write to a zero-length buffer. This causes
kernel oops in the receiving guest and hangs its xenbus kernel thread.
The patch returns -EINVAL in that case.
Signed-off-by: Haogang Chen <haogangchen@xxxxxxxxx>
---
drivers/xen/xenbus/xenbus_xs.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index ede860f..e32aefb 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -801,6 +801,12 @@ static int process_msg(void)
goto out;
}
+ if (msg->hdr.len == UINT_MAX) {
+ kfree(msg);
+ err = -EINVAL;
+ goto out;
+ }
+
body = kmalloc(msg->hdr.len + 1, GFP_NOIO | __GFP_HIGH);
if (body == NULL) {
kfree(msg);
--
1.7.5.4
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