From 304a654a0d57bf0f00d8998185f0360332cfa36c Mon Sep 17 00:00:00 2001 From: Alan Coopersmith Date: Sat, 10 Jun 2023 16:30:07 -0700 Subject: [PATCH libX11] InitExt.c: Add bounds checks for extension request, event, & error codes Fixes CVE-2023-3138: X servers could return values from XQueryExtension that would cause Xlib to write entries out-of-bounds of the arrays to store them, though this would only overwrite other parts of the Display struct, not outside the bounds allocated for that structure. Reported-by: Gregory James DUCK Signed-off-by: Alan Coopersmith --- src/InitExt.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/src/InitExt.c b/src/InitExt.c index 4de46f15..afc00a6b 100644 --- a/src/InitExt.c +++ b/src/InitExt.c @@ -33,6 +33,18 @@ from The Open Group. #include #include +/* The X11 protocol spec reserves events 64 through 127 for extensions */ +#ifndef LastExtensionEvent +#define LastExtensionEvent 127 +#endif + +/* The X11 protocol spec reserves requests 128 through 255 for extensions */ +#ifndef LastExtensionRequest +#define FirstExtensionRequest 128 +#define LastExtensionRequest 255 +#endif + + /* * This routine is used to link a extension in so it will be called * at appropriate times. @@ -242,6 +254,12 @@ WireToEventType XESetWireToEvent( WireToEventType proc) /* routine to call when converting event */ { register WireToEventType oldproc; + if (event_number < 0 || + event_number > LastExtensionEvent) { + fprintf(stderr, "Xlib: ignoring invalid extension event %d\n", + event_number); + return (WireToEventType)_XUnknownWireEvent; + } if (proc == NULL) proc = (WireToEventType)_XUnknownWireEvent; LockDisplay (dpy); oldproc = dpy->event_vec[event_number]; @@ -263,6 +281,12 @@ WireToEventCookieType XESetWireToEventCookie( ) { WireToEventCookieType oldproc; + if (extension < FirstExtensionRequest || + extension > LastExtensionRequest) { + fprintf(stderr, "Xlib: ignoring invalid extension opcode %d\n", + extension); + return (WireToEventCookieType)_XUnknownWireEventCookie; + } if (proc == NULL) proc = (WireToEventCookieType)_XUnknownWireEventCookie; LockDisplay (dpy); oldproc = dpy->generic_event_vec[extension & 0x7F]; @@ -284,6 +308,12 @@ CopyEventCookieType XESetCopyEventCookie( ) { CopyEventCookieType oldproc; + if (extension < FirstExtensionRequest || + extension > LastExtensionRequest) { + fprintf(stderr, "Xlib: ignoring invalid extension opcode %d\n", + extension); + return (CopyEventCookieType)_XUnknownCopyEventCookie; + } if (proc == NULL) proc = (CopyEventCookieType)_XUnknownCopyEventCookie; LockDisplay (dpy); oldproc = dpy->generic_event_copy_vec[extension & 0x7F]; @@ -305,6 +335,12 @@ EventToWireType XESetEventToWire( EventToWireType proc) /* routine to call when converting event */ { register EventToWireType oldproc; + if (event_number < 0 || + event_number > LastExtensionEvent) { + fprintf(stderr, "Xlib: ignoring invalid extension event %d\n", + event_number); + return (EventToWireType)_XUnknownNativeEvent; + } if (proc == NULL) proc = (EventToWireType) _XUnknownNativeEvent; LockDisplay (dpy); oldproc = dpy->wire_vec[event_number]; @@ -325,6 +361,12 @@ WireToErrorType XESetWireToError( WireToErrorType proc) /* routine to call when converting error */ { register WireToErrorType oldproc = NULL; + if (error_number < 0 || + error_number > LastExtensionError) { + fprintf(stderr, "Xlib: ignoring invalid extension error %d\n", + error_number); + return (WireToErrorType)_XDefaultWireError; + } if (proc == NULL) proc = (WireToErrorType)_XDefaultWireError; LockDisplay (dpy); if (!dpy->error_vec) { -- 2.41.0