fs: binfmt_elf_efpic: don't use missing interpreter's properties

Static FDPIC executable may get an executable stack even when it has non-executable GNU_STACK segment. This happens when STACK segment has rw permissions, but does not specify stack size. In that case FDPIC loader uses permissions of the interpreter's stack, and for static executables with no interpreter it results in choosing the arch-default permissions for the stack.

Fix that by using the interpreter's properties only when the interpreter is actually used.

Signed-off-by Max Filippov <[email protected]>

---
 fs/binfmt_elf_fdpic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

fs/binfmt_elf_fdpic.c +1 -2

index be4e7ac3efbc..f6d72fe3998c 100644
@@ -322,7 +322,7 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
        else
                executable_stack = EXSTACK_DEFAULT;
 
-       if (stack_size == 0) {
+       if (stack_size == 0 && interp_params.flags & ELF_FDPIC_FLAG_PRESENT) {
                stack_size = interp_params.stack_size;
                if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
                        executable_stack = EXSTACK_ENABLE_X;
--

2.39.2

Static FDPIC executable may get an executable stack even when it has non-executable GNU_STACK segment. This happens when STACK segment has rw permissions, but does not specify stack size. In that case FDPIC loader uses permissions of the interpreter's stack, and for static executables with no interpreter it results in choosing the arch-default permissions for the stack.

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