x86/mpx: Restrict the mmap() size check to bounds tables

The comment and code here are confusing.  We do not currently
allocate the bounds directory in the kernel.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183702.222CEC2A@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 47e4a8564012deb3a5c4bff84ef52cb88ba2dd6b..d6e02f3adee0911299189f9ff13fbf200a4aad51 100644 (file)
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -46,8 +46,8 @@ static unsigned long mpx_mmap(unsigned long len)
        vm_flags_t vm_flags;
        struct vm_area_struct *vma;
 
-       /* Only bounds table and bounds directory can be allocated here */
-       if (len != MPX_BD_SIZE_BYTES && len != MPX_BT_SIZE_BYTES)
+       /* Only bounds table can be allocated here */
+       if (len != MPX_BT_SIZE_BYTES)
                return -EINVAL;
 
        down_write(&mm->mmap_sem);