https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65696
--- Comment #3 from pmderodat at gcc dot gnu.org --- Author: pmderodat Date: Mon Aug 19 08:36:39 2019 New Revision: 274654 URL: https://gcc.gnu.org/viewcvs?rev=274654&root=gcc&view=rev Log: [Ada] Buffer reading overflow in dispatch table initialization For tagged types not defined at library level that derive from library level tagged types the compiler may generate code to initialize their dispatch table of predefined primitives copying from the parent type data stored in memory after the dispatch table of the parent; that is, at runtime the initialization of dispatch tables overflows reading the parent dispatch table. This problem does not affect the execution of the program since the target dispatch table always has enough space to store the extra data, and after such copy the compiler generates code to complete the initialization of the dispatch table. The following test must compile and execute without errors. package pkg_a is type Root is tagged null record; end pkg_a; with pkg_a; procedure main is type Derived is new pkg_a.Root with null record; -- Test begin null; end main; Command: gnatmake -q main -fsanitize=address; ./main 2019-08-19 Javier Miranda <mira...@adacore.com> gcc/ada/ PR ada/65696 * exp_atag.ads, exp_atag.adb (Build_Inherit_Predefined_Prims): Adding formal to specify how many predefined primitives are inherited from the parent type. * exp_disp.adb (Number_Of_Predefined_Prims): New subprogram. (Make_Secondary_DT): Compute the number of predefined primitives of all tagged types (including tagged types not defined at library level). Previously we unconditionally relied on the Max_Predef_Prims constant value when building the dispatch tables of tagged types not defined at library level (thus consuming more memory for their dispatch tables than required). (Make_DT): Compute the number of predefined primitives that must be inherited from their parent type when building the dispatch tables of tagged types not defined at library level. Previously we unconditionally relied on the Max_Predef_Prims constant value when building the dispatch tables of tagged types not defined at library level (thus copying more data than required from the parent type). Modified: trunk/gcc/ada/ChangeLog trunk/gcc/ada/exp_atag.adb trunk/gcc/ada/exp_atag.ads trunk/gcc/ada/exp_disp.adb
