IMO users ought not to be able to use 16-bit segments without using modify_ldt. Fortunately, it's impossible to break espfix64 by loading the PER_CPU segment into SS because it's a read-only segment, but marking it 32-bit seems less fragile.
Signed-off-by: Andy Lutomirski <[email protected]> --- arch/x86/kernel/vsyscall_64.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c index 0e2c229..87ab841 100644 --- a/arch/x86/kernel/vsyscall_64.c +++ b/arch/x86/kernel/vsyscall_64.c @@ -309,6 +309,7 @@ static void vsyscall_set_cpu(int cpu) d.dpl = 3; /* Visible to user code */ d.s = 1; /* Non a system segment */ d.p = 1; /* Present */ + d.d = 1; /* 32-bit */ write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S); } -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
