x86-64: Pad vDSO to a page boundary

This avoids an information leak to userspace.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/a63380a3c58a0506a2f5a18ba1b12dbde1f25e58.1312378163.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/vdso/vdso.S b/arch/x86/vdso/vdso.S
index 1b979c1..01f5e3b 100644 (file)
--- a/arch/x86/vdso/vdso.S
+++ b/arch/x86/vdso/vdso.S
@@ -9,6 +9,7 @@ __PAGE_ALIGNED_DATA
 vdso_start:
        .incbin "arch/x86/vdso/vdso.so"
 vdso_end:
+       .align PAGE_SIZE /* extra data here leaks to userspace. */
 
 .previous