use H5_IS_BUFFER_OVERFLOW to check overflow

Author: oss-patch

src/H5Faccum.c

@@ -881,10 +881,10 @@ H5F__accum_free(H5F_shared_t *f_sh, H5FD_mem_t H5_ATTR_UNUSED type, haddr_t addr
                 H5_CHECKED_ASSIGN(overlap_size, size_t, (addr + size) - accum->loc, haddr_t);
                 new_accum_size = accum->size - overlap_size;
 
-                /* Ensure overlap_size and new_accum_size are within bounds */
-                if (overlap_size > accum->alloc_size || new_accum_size > accum->alloc_size) {
-                    HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL,
-                                "calculated sizes exceed allocated buffer size");
+                /* Ensure that the memmove operation won't overflow past the buffer's allocated size */
+                if (H5_IS_BUFFER_OVERFLOW(accum->buf + overlap_size, new_accum_size, accum->buf + accum->alloc_size)) {
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, 
+                                "memmove operation would overflow buffer");
                 }
 
                 /* Move the accumulator buffer information to eliminate the freed block */