[libvirt] [PATCHv2] uml: sanity check external data before using it

[Eric Blake <eblake@xxxxxxxxxx>]

Otherwise, a malicious packet could cause a DoS via spurious
out-of-memory failure.

* src/uml/uml_driver.c (umlMonitorCommand): Validate that incoming
data is reliable before using it to allocate/dereference memory.
Don't report bogus errno on short read.
Reported by Jim Meyering.
---
 src/uml/uml_driver.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/uml/uml_driver.c b/src/uml/uml_driver.c
index eec239f..4a5db9d 100644
--- a/src/uml/uml_driver.c
+++ b/src/uml/uml_driver.c
@@ -740,15 +740,15 @@ static int umlMonitorCommand(virConnectPtr conn,
         if (nbytes < 0) {
             if (errno == EAGAIN || errno == EINTR)
                 continue;
-            virReportSystemError(errno,
-                                 _("cannot read reply %s"),
-                                 cmd);
+            virReportSystemError(errno, _("cannot read reply %s"), cmd);
             goto error;
         }
         if (nbytes < sizeof res) {
-            virReportSystemError(errno,
-                                 _("incomplete reply %s"),
-                                 cmd);
+            virReportSystemError(0, _("incomplete reply %s"), cmd);
+            goto error;
+        }
+        if (sizeof res.data < res.length) {
+            virReportSystemError(0, _("invalid length in reply %s"), cmd);
             goto error;
         }

-- 
1.6.6.1

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