diff options
| -rw-r--r-- | libvncserver/rfbserver.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/libvncserver/rfbserver.c b/libvncserver/rfbserver.c index 116c488..4fc4d9d 100644 --- a/libvncserver/rfbserver.c +++ b/libvncserver/rfbserver.c @@ -88,6 +88,8 @@ #include <errno.h> /* strftime() */ #include <time.h> +/* PRIu32 */ +#include <inttypes.h> #ifdef LIBVNCSERVER_WITH_WEBSOCKETS #include "rfbssl.h" @@ -2575,7 +2577,23 @@ rfbProcessClientNormalMessage(rfbClientPtr 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 (str == NULL) { rfbLogPerror("rfbProcessClientNormalMessage: not enough memory"); rfbCloseClient(cl); |