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Message-Id: <43d8d7cb108afa99d34f2b16d965e8304ff951e1.1406757779.git.luto@amacapital.net> Date: Wed, 30 Jul 2014 15:07:05 -0700 From: Andy Lutomirski <luto@...capital.net> To: hpa@...or.com, x86@...nel.org, linux-kernel@...r.kernel.org Cc: Andy Lutomirski <luto@...capital.net> Subject: [PATCH v2 3/3] x86,vdso: Make the PER_CPU segment 32 bits 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 <luto@...capital.net> --- 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 ae80ef6..0d71181 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; /* Not 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 majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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