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-rw-r--r--krfb/libvncserver/rfbserver.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/krfb/libvncserver/rfbserver.c b/krfb/libvncserver/rfbserver.c
index 66cc4ee3..5725d068 100644
--- a/krfb/libvncserver/rfbserver.c
+++ b/krfb/libvncserver/rfbserver.c
@@ -52,6 +52,9 @@ typedef int socklen_t;
#define DEBUGPROTO(x)
#endif
+/* PRIu32 */
+#include <inttypes.h>
+
rfbClientPtr pointerClient = NULL; /* Mutex for pointer events */
static void rfbProcessClientProtocolVersion(rfbClientPtr cl);
@@ -898,7 +901,23 @@ rfbProcessClientNormalMessage(cl)
msg.cct.length = Swap32IfLE(msg.cct.length);
- str = (char *)malloc(msg.cct.length);
+ /* uint32_t input is passed to malloc()'s size_t argument,
+ * to rfbReadExact()'s int argument, to rfbStatRecordMessageRcvd()'s int
+ * argument increased of sz_rfbClientCutTextMsg, and to setXCutText()'s int
+ * argument. Here we impose a limit of 1 MB so that the value fits
+ * into all of the types to prevent from misinterpretation and thus
+ * from accessing uninitialized memory (CVE-2018-7225) and also to
+ * prevent from a denial-of-service by allocating to much memory in
+ * the server. */
+ if (msg.cct.length > 1<<20) {
+ rfbLog("rfbClientCutText: too big cut text length requested: %" PRIu32 "\n",
+ msg.cct.length);
+ rfbCloseClient(cl);
+ return;
+ }
+
+ /* Allow zero-length client cut text. */
+ str = (char *)calloc(msg.cct.length ? msg.cct.length : 1, 1);
if ((n = ReadExact(cl, str, msg.cct.length)) <= 0) {
if (n != 0)