fs/binfmt_elf: fix PT_LOAD p_align values for loaders

Rui Salvaterra reported that Aisleroit solitaire crashes with "Wrong
__data_start/_end pair" assertion from libgc after update to v5.17-rc1.

Bisection pointed to commit 9630f0d ("fs/binfmt_elf: use PT_LOAD
p_align values for static PIE") that fixed handling of static PIEs, but
made the condition that guards load_bias calculation to exclude loader
binaries.

Restoring the check for presence of interpreter fixes the problem.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 9630f0d ("fs/binfmt_elf: use PT_LOAD p_align values for static PIE")
Signed-off-by: Mike Rapoport <[email protected]>
Reported-by: Rui Salvaterra <[email protected]>
Tested-by: Rui Salvaterra <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Eric Biederman <[email protected]>
Cc: "H.J. Lu" <[email protected]>
Cc: Kees Cook <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/binfmt_elf.c

@@ -1117,7 +1117,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
 			 * without MAP_FIXED nor MAP_FIXED_NOREPLACE).
 			 */
 			alignment = maximum_alignment(elf_phdata, elf_ex->e_phnum);
-			if (alignment > ELF_MIN_ALIGN) {
+			if (interpreter || alignment > ELF_MIN_ALIGN) {
 				load_bias = ELF_ET_DYN_BASE;
 				if (current->flags & PF_RANDOMIZE)
 					load_bias += arch_mmap_rnd();