On Tue, Nov 18, 2014 at 9:40 AM, tip-bot for Kees Cook <tipbot@xxxxxxxxx> wrote: > Commit-ID: 45e2a9d4701d8c624d4a4bcdd1084eae31e92f58 > Gitweb: http://git.kernel.org/tip/45e2a9d4701d8c624d4a4bcdd1084eae31e92f58 > Author: Kees Cook <keescook@xxxxxxxxxxxx> > AuthorDate: Fri, 14 Nov 2014 11:47:37 -0800 > Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > CommitDate: Tue, 18 Nov 2014 18:32:24 +0100 > > x86, mm: Set NX across entire PMD at boot > > When setting up permissions on kernel memory at boot, the end of the > PMD that was split from bss remained executable. It should be NX like > the rest. This performs a PMD alignment instead of a PAGE alignment to > get the correct span of memory. > > Before: > ---[ High Kernel Mapping ]--- > ... > 0xffffffff8202d000-0xffffffff82200000 1868K RW GLB NX pte > 0xffffffff82200000-0xffffffff82c00000 10M RW PSE GLB NX pmd > 0xffffffff82c00000-0xffffffff82df5000 2004K RW GLB NX pte > 0xffffffff82df5000-0xffffffff82e00000 44K RW GLB x pte > 0xffffffff82e00000-0xffffffffc0000000 978M pmd > > After: > ---[ High Kernel Mapping ]--- > ... > 0xffffffff8202d000-0xffffffff82200000 1868K RW GLB NX pte > 0xffffffff82200000-0xffffffff82e00000 12M RW PSE GLB NX pmd > 0xffffffff82e00000-0xffffffffc0000000 978M pmd > > [ tglx: Changed it to roundup(_brk_end, PMD_SIZE) and added a comment. > We really should unmap the reminder along with the holes > caused by init,initdata etc. but thats a different issue ] > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> > Cc: Toshi Kani <toshi.kani@xxxxxx> > Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> > Cc: David Vrabel <david.vrabel@xxxxxxxxxx> > Cc: Wang Nan <wangnan0@xxxxxxxxxx> > Cc: Yinghai Lu <yinghai@xxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > Link: http://lkml.kernel.org/r/20141114194737.GA3091@xxxxxxxxxxxxxxx > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > --- > arch/x86/mm/init_64.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 4cb8763..4e5dfec 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1123,7 +1123,7 @@ void mark_rodata_ro(void) > unsigned long end = (unsigned long) &__end_rodata_hpage_align; > unsigned long text_end = PFN_ALIGN(&__stop___ex_table); > unsigned long rodata_end = PFN_ALIGN(&__end_rodata); > - unsigned long all_end = PFN_ALIGN(&_end); > + unsigned long all_end; > > printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n", > (end - start) >> 10); > @@ -1134,7 +1134,16 @@ void mark_rodata_ro(void) > /* > * The rodata/data/bss/brk section (but not the kernel text!) > * should also be not-executable. > + * > + * We align all_end to PMD_SIZE because the existing mapping > + * is a full PMD. If we would align _brk_end to PAGE_SIZE we > + * split the PMD and the reminder between _brk_end and the end > + * of the PMD will remain mapped executable. > + * > + * Any PMD which was setup after the one which covers _brk_end > + * has been zapped already via cleanup_highmem(). should be cleanup_highmap() > */ > + all_end = roundup((unsigned long)_brk_end, PMD_SIZE); Why do you need cast here ? > set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT); > > rodata_test(); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|