FreeBSD _umtx_op: fix bad wrapper for robust lists

Was a half-baked copy and paste from the mutex version.

diff --git a/coregrind/m_syswrap/syswrap-freebsd.c b/coregrind/m_syswrap/syswrap-freebsd.c
index 18717a89724a444487b65eeb48c9e9edd0b2362d..d2116843321931230155d4eaf996c5172c0549ff 100644 (file)
--- a/coregrind/m_syswrap/syswrap-freebsd.c
+++ b/coregrind/m_syswrap/syswrap-freebsd.c
@@ -4696,15 +4696,19 @@ PRE(sys__umtx_op)
                     void *, obj, int, op, unsigned long, val, void*, uaddr);
       break;
    case VKI_UMTX_OP_ROBUST_LISTS:
-      // val (ARG2) ought to be the same as sizeof(struct vki_umtx_robust_lists_params)
-      // then the structure contains a pointer to mutex structures
-      if (ARG1 != sizeof(struct vki_umtx_robust_lists_params)) {
-         SET_STATUS_Failure( VKI_ENOSYS );
+      // strangely the obj pointer ARG1 isn't used, for instance lin libc
+      // libthr/thread/thr_mutex.c:      _umtx_op(NULL, UMTX_OP_ROBUST_LISTS, sizeof(rb), &rb, NULL);
+      // val (ARG3) ought to be the same as sizeof(struct vki_umtx_robust_lists_params)
+      // strangely the kernel returns EINVAL if size is larger than sizeof(struct vki_umtx_robust_lists_params)
+      // (which seems relatively harmless)
+      // but not if it is smaller (definitely dangerous, probably an overrun)
+      if (ARG3 < sizeof(struct vki_umtx_robust_lists_params)) {
+         VG_(umsg)("WARNING: _umtx_op_tobust_lists size is smaller than sizeof(struct umtx_robust_lists_params).\n");
       }
       PRINT( "sys__umtx_op ( %#" FMT_REGWORD "x, ROBUST_LISTS, %" FMT_REGWORD "u, %#" FMT_REGWORD "x, %#" FMT_REGWORD "x)", ARG1, ARG3, ARG4, ARG5);
-      PRE_REG_READ3(long, "_umtx_op_robust_lists",
-                    struct umtx_robust_lists_params *, obj, int, op, unsigned long, flags);
-      PRE_MEM_READ( "_umtx_op_robust_lists(mutex)", ARG3, sizeof(struct vki_umtx_robust_lists_params) );
+      PRE_REG_READ4(long, "_umtx_op_robust_lists",
+                    void*, obj, int, op, unsigned long, val, struct umtx_robust_lists*, uaddr);
+      PRE_MEM_READ( "_umtx_op_robust_lists(robust_lists)", ARG4, ARG3 );
       break;
 #if (FREEBSD_VERS >= FREEBSD_13_3)
    case VKI_UMTX_OP_GET_MIN_TIMEOUT: