* Re: x86: Make sure IDT is page aligned [not found] <20130719011526.15FA46608B1@gitolite.kernel.org> @ 2013-07-19 1:30 ` Greg KH 2013-07-19 1:36 ` Kees Cook 0 siblings, 1 reply; 4+ messages in thread From: Greg KH @ 2013-07-19 1:30 UTC (permalink / raw) To: Kees Cook, PaX Team, H. Peter Anvin; +Cc: linux-kernel On Fri, Jul 19, 2013 at 01:15:26AM +0000, Linux Kernel Mailing List wrote: > Gitweb: http://git.kernel.org/linus/;a=commit;h=4df05f361937ee86e5a8c9ead8aeb6a19ea9b7d7 > Commit: 4df05f361937ee86e5a8c9ead8aeb6a19ea9b7d7 > Parent: 5ff560fd48d5b3d82fa0c3aff625c9da1a301911 > Author: Kees Cook <keescook@chromium.org> > AuthorDate: Tue Jul 16 11:34:41 2013 -0700 > Committer: H. Peter Anvin <hpa@linux.intel.com> > CommitDate: Tue Jul 16 15:14:48 2013 -0700 > > x86: Make sure IDT is page aligned > > Since the IDT is referenced from a fixmap, make sure it is page aligned. > Merge with 32-bit one, since it was already aligned to deal with F00F > bug. Since bss is cleared before IDT setup, it can live there. This also > moves the other *_idt_table variables into common locations. > > This avoids the risk of the IDT ever being moved in the bss and having > the mapping be offset, resulting in calling incorrect handlers. In the > current upstream kernel this is not a manifested bug, but heavily patched > kernels (such as those using the PaX patch series) did encounter this bug. > > The tables other than idt_table technically do not need to be page > aligned, at least not at the current time, but using a common > declaration avoids mistakes. On 64 bits the table is exactly one page > long, anyway. > > Signed-off-by: Kees Cook <keescook@chromium.org> > Link: http://lkml.kernel.org/r/20130716183441.GA14232@www.outflux.net > Reported-by: PaX Team <pageexec@gmail.com> > Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> > --- > arch/x86/kernel/head_64.S | 15 --------------- > arch/x86/kernel/tracepoint.c | 6 ++---- > arch/x86/kernel/traps.c | 12 ++++++------ > 3 files changed, 8 insertions(+), 25 deletions(-) This patch is now in Linus's tree. Kees, did you also want this in the -stable tree(s)? thanks, greg k-h > > diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S > index 5e4d8a8..e1aabdb 100644 > --- a/arch/x86/kernel/head_64.S > +++ b/arch/x86/kernel/head_64.S > @@ -512,21 +512,6 @@ ENTRY(phys_base) > > #include "../../x86/xen/xen-head.S" > > - .section .bss, "aw", @nobits > - .align L1_CACHE_BYTES > -ENTRY(idt_table) > - .skip IDT_ENTRIES * 16 > - > - .align L1_CACHE_BYTES > -ENTRY(debug_idt_table) > - .skip IDT_ENTRIES * 16 > - > -#ifdef CONFIG_TRACING > - .align L1_CACHE_BYTES > -ENTRY(trace_idt_table) > - .skip IDT_ENTRIES * 16 > -#endif > - > __PAGE_ALIGNED_BSS > NEXT_PAGE(empty_zero_page) > .skip PAGE_SIZE > diff --git a/arch/x86/kernel/tracepoint.c b/arch/x86/kernel/tracepoint.c > index 4e584a8..1c113db 100644 > --- a/arch/x86/kernel/tracepoint.c > +++ b/arch/x86/kernel/tracepoint.c > @@ -12,10 +12,8 @@ atomic_t trace_idt_ctr = ATOMIC_INIT(0); > struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1, > (unsigned long) trace_idt_table }; > > -#ifndef CONFIG_X86_64 > -gate_desc trace_idt_table[NR_VECTORS] __page_aligned_data > - = { { { { 0, 0 } } }, }; > -#endif > +/* No need to be aligned, but done to keep all IDTs defined the same way. */ > +gate_desc trace_idt_table[NR_VECTORS] __page_aligned_bss; > > static int trace_irq_vector_refcount; > static DEFINE_MUTEX(irq_vector_mutex); > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > index b0865e8..1b23a1c 100644 > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -63,19 +63,19 @@ > #include <asm/x86_init.h> > #include <asm/pgalloc.h> > #include <asm/proto.h> > + > +/* No need to be aligned, but done to keep all IDTs defined the same way. */ > +gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss; > #else > #include <asm/processor-flags.h> > #include <asm/setup.h> > > asmlinkage int system_call(void); > - > -/* > - * The IDT has to be page-aligned to simplify the Pentium > - * F0 0F bug workaround. > - */ > -gate_desc idt_table[NR_VECTORS] __page_aligned_data = { { { { 0, 0 } } }, }; > #endif > > +/* Must be page-aligned because the real IDT is used in a fixmap. */ > +gate_desc idt_table[NR_VECTORS] __page_aligned_bss; > + > DECLARE_BITMAP(used_vectors, NR_VECTORS); > EXPORT_SYMBOL_GPL(used_vectors); > > -- > To unsubscribe from this list: send the line "unsubscribe git-commits-head" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: x86: Make sure IDT is page aligned 2013-07-19 1:30 ` x86: Make sure IDT is page aligned Greg KH @ 2013-07-19 1:36 ` Kees Cook 2013-07-19 1:50 ` Greg KH 0 siblings, 1 reply; 4+ messages in thread From: Kees Cook @ 2013-07-19 1:36 UTC (permalink / raw) To: Greg KH; +Cc: PaX Team, H. Peter Anvin, LKML On Thu, Jul 18, 2013 at 6:30 PM, Greg KH <gregkh@linuxfoundation.org> wrote: > On Fri, Jul 19, 2013 at 01:15:26AM +0000, Linux Kernel Mailing List wrote: >> Gitweb: http://git.kernel.org/linus/;a=commit;h=4df05f361937ee86e5a8c9ead8aeb6a19ea9b7d7 >> Commit: 4df05f361937ee86e5a8c9ead8aeb6a19ea9b7d7 >> Parent: 5ff560fd48d5b3d82fa0c3aff625c9da1a301911 >> Author: Kees Cook <keescook@chromium.org> >> AuthorDate: Tue Jul 16 11:34:41 2013 -0700 >> Committer: H. Peter Anvin <hpa@linux.intel.com> >> CommitDate: Tue Jul 16 15:14:48 2013 -0700 >> >> x86: Make sure IDT is page aligned >> >> Since the IDT is referenced from a fixmap, make sure it is page aligned. >> Merge with 32-bit one, since it was already aligned to deal with F00F >> bug. Since bss is cleared before IDT setup, it can live there. This also >> moves the other *_idt_table variables into common locations. >> >> This avoids the risk of the IDT ever being moved in the bss and having >> the mapping be offset, resulting in calling incorrect handlers. In the >> current upstream kernel this is not a manifested bug, but heavily patched >> kernels (such as those using the PaX patch series) did encounter this bug. >> >> The tables other than idt_table technically do not need to be page >> aligned, at least not at the current time, but using a common >> declaration avoids mistakes. On 64 bits the table is exactly one page >> long, anyway. >> >> Signed-off-by: Kees Cook <keescook@chromium.org> >> Link: http://lkml.kernel.org/r/20130716183441.GA14232@www.outflux.net >> Reported-by: PaX Team <pageexec@gmail.com> >> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> >> --- >> arch/x86/kernel/head_64.S | 15 --------------- >> arch/x86/kernel/tracepoint.c | 6 ++---- >> arch/x86/kernel/traps.c | 12 ++++++------ >> 3 files changed, 8 insertions(+), 25 deletions(-) > > This patch is now in Linus's tree. Kees, did you also want this in the > -stable tree(s)? The potential problem was introduced with 4eefbe792baedb474e256d35370849992fcf1c79, so 3.10 needs it, yes. I had also sent a much smaller version here: http://git.kernel.org/cgit/linux/kernel/git/kees/linux.git/commit/?h=idt-stable&id=794c1e0df641e13050cfc4af340fc3c85bed4ea3 Either will address the problem. If there is no problem with taking the larger clean-up for stable, then that's probably easiest. Thanks! -Kees > > thanks, > > greg k-h > > >> >> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S >> index 5e4d8a8..e1aabdb 100644 >> --- a/arch/x86/kernel/head_64.S >> +++ b/arch/x86/kernel/head_64.S >> @@ -512,21 +512,6 @@ ENTRY(phys_base) >> >> #include "../../x86/xen/xen-head.S" >> >> - .section .bss, "aw", @nobits >> - .align L1_CACHE_BYTES >> -ENTRY(idt_table) >> - .skip IDT_ENTRIES * 16 >> - >> - .align L1_CACHE_BYTES >> -ENTRY(debug_idt_table) >> - .skip IDT_ENTRIES * 16 >> - >> -#ifdef CONFIG_TRACING >> - .align L1_CACHE_BYTES >> -ENTRY(trace_idt_table) >> - .skip IDT_ENTRIES * 16 >> -#endif >> - >> __PAGE_ALIGNED_BSS >> NEXT_PAGE(empty_zero_page) >> .skip PAGE_SIZE >> diff --git a/arch/x86/kernel/tracepoint.c b/arch/x86/kernel/tracepoint.c >> index 4e584a8..1c113db 100644 >> --- a/arch/x86/kernel/tracepoint.c >> +++ b/arch/x86/kernel/tracepoint.c >> @@ -12,10 +12,8 @@ atomic_t trace_idt_ctr = ATOMIC_INIT(0); >> struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1, >> (unsigned long) trace_idt_table }; >> >> -#ifndef CONFIG_X86_64 >> -gate_desc trace_idt_table[NR_VECTORS] __page_aligned_data >> - = { { { { 0, 0 } } }, }; >> -#endif >> +/* No need to be aligned, but done to keep all IDTs defined the same way. */ >> +gate_desc trace_idt_table[NR_VECTORS] __page_aligned_bss; >> >> static int trace_irq_vector_refcount; >> static DEFINE_MUTEX(irq_vector_mutex); >> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c >> index b0865e8..1b23a1c 100644 >> --- a/arch/x86/kernel/traps.c >> +++ b/arch/x86/kernel/traps.c >> @@ -63,19 +63,19 @@ >> #include <asm/x86_init.h> >> #include <asm/pgalloc.h> >> #include <asm/proto.h> >> + >> +/* No need to be aligned, but done to keep all IDTs defined the same way. */ >> +gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss; >> #else >> #include <asm/processor-flags.h> >> #include <asm/setup.h> >> >> asmlinkage int system_call(void); >> - >> -/* >> - * The IDT has to be page-aligned to simplify the Pentium >> - * F0 0F bug workaround. >> - */ >> -gate_desc idt_table[NR_VECTORS] __page_aligned_data = { { { { 0, 0 } } }, }; >> #endif >> >> +/* Must be page-aligned because the real IDT is used in a fixmap. */ >> +gate_desc idt_table[NR_VECTORS] __page_aligned_bss; >> + >> DECLARE_BITMAP(used_vectors, NR_VECTORS); >> EXPORT_SYMBOL_GPL(used_vectors); >> >> -- >> To unsubscribe from this list: send the line "unsubscribe git-commits-head" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- Kees Cook Chrome OS Security ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: x86: Make sure IDT is page aligned 2013-07-19 1:36 ` Kees Cook @ 2013-07-19 1:50 ` Greg KH 2013-08-01 3:12 ` Greg KH 0 siblings, 1 reply; 4+ messages in thread From: Greg KH @ 2013-07-19 1:50 UTC (permalink / raw) To: Kees Cook; +Cc: PaX Team, H. Peter Anvin, LKML On Thu, Jul 18, 2013 at 06:36:07PM -0700, Kees Cook wrote: > On Thu, Jul 18, 2013 at 6:30 PM, Greg KH <gregkh@linuxfoundation.org> wrote: > > On Fri, Jul 19, 2013 at 01:15:26AM +0000, Linux Kernel Mailing List wrote: > >> Gitweb: http://git.kernel.org/linus/;a=commit;h=4df05f361937ee86e5a8c9ead8aeb6a19ea9b7d7 > >> Commit: 4df05f361937ee86e5a8c9ead8aeb6a19ea9b7d7 > >> Parent: 5ff560fd48d5b3d82fa0c3aff625c9da1a301911 > >> Author: Kees Cook <keescook@chromium.org> > >> AuthorDate: Tue Jul 16 11:34:41 2013 -0700 > >> Committer: H. Peter Anvin <hpa@linux.intel.com> > >> CommitDate: Tue Jul 16 15:14:48 2013 -0700 > >> > >> x86: Make sure IDT is page aligned > >> > >> Since the IDT is referenced from a fixmap, make sure it is page aligned. > >> Merge with 32-bit one, since it was already aligned to deal with F00F > >> bug. Since bss is cleared before IDT setup, it can live there. This also > >> moves the other *_idt_table variables into common locations. > >> > >> This avoids the risk of the IDT ever being moved in the bss and having > >> the mapping be offset, resulting in calling incorrect handlers. In the > >> current upstream kernel this is not a manifested bug, but heavily patched > >> kernels (such as those using the PaX patch series) did encounter this bug. > >> > >> The tables other than idt_table technically do not need to be page > >> aligned, at least not at the current time, but using a common > >> declaration avoids mistakes. On 64 bits the table is exactly one page > >> long, anyway. > >> > >> Signed-off-by: Kees Cook <keescook@chromium.org> > >> Link: http://lkml.kernel.org/r/20130716183441.GA14232@www.outflux.net > >> Reported-by: PaX Team <pageexec@gmail.com> > >> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> > >> --- > >> arch/x86/kernel/head_64.S | 15 --------------- > >> arch/x86/kernel/tracepoint.c | 6 ++---- > >> arch/x86/kernel/traps.c | 12 ++++++------ > >> 3 files changed, 8 insertions(+), 25 deletions(-) > > > > This patch is now in Linus's tree. Kees, did you also want this in the > > -stable tree(s)? > > The potential problem was introduced with > 4eefbe792baedb474e256d35370849992fcf1c79, so 3.10 needs it, yes. I had > also sent a much smaller version here: > http://git.kernel.org/cgit/linux/kernel/git/kees/linux.git/commit/?h=idt-stable&id=794c1e0df641e13050cfc4af340fc3c85bed4ea3 > > Either will address the problem. If there is no problem with taking > the larger clean-up for stable, then that's probably easiest. I'd prefer to stick with what ended up in Linus's tree, so I'll just queue this one up in a future stable 3.10 release, thanks. greg k-h ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: x86: Make sure IDT is page aligned 2013-07-19 1:50 ` Greg KH @ 2013-08-01 3:12 ` Greg KH 0 siblings, 0 replies; 4+ messages in thread From: Greg KH @ 2013-08-01 3:12 UTC (permalink / raw) To: Kees Cook; +Cc: PaX Team, H. Peter Anvin, LKML On Thu, Jul 18, 2013 at 06:50:55PM -0700, Greg KH wrote: > On Thu, Jul 18, 2013 at 06:36:07PM -0700, Kees Cook wrote: > > On Thu, Jul 18, 2013 at 6:30 PM, Greg KH <gregkh@linuxfoundation.org> wrote: > > > On Fri, Jul 19, 2013 at 01:15:26AM +0000, Linux Kernel Mailing List wrote: > > >> Gitweb: http://git.kernel.org/linus/;a=commit;h=4df05f361937ee86e5a8c9ead8aeb6a19ea9b7d7 > > >> Commit: 4df05f361937ee86e5a8c9ead8aeb6a19ea9b7d7 > > >> Parent: 5ff560fd48d5b3d82fa0c3aff625c9da1a301911 > > >> Author: Kees Cook <keescook@chromium.org> > > >> AuthorDate: Tue Jul 16 11:34:41 2013 -0700 > > >> Committer: H. Peter Anvin <hpa@linux.intel.com> > > >> CommitDate: Tue Jul 16 15:14:48 2013 -0700 > > >> > > >> x86: Make sure IDT is page aligned > > >> > > >> Since the IDT is referenced from a fixmap, make sure it is page aligned. > > >> Merge with 32-bit one, since it was already aligned to deal with F00F > > >> bug. Since bss is cleared before IDT setup, it can live there. This also > > >> moves the other *_idt_table variables into common locations. > > >> > > >> This avoids the risk of the IDT ever being moved in the bss and having > > >> the mapping be offset, resulting in calling incorrect handlers. In the > > >> current upstream kernel this is not a manifested bug, but heavily patched > > >> kernels (such as those using the PaX patch series) did encounter this bug. > > >> > > >> The tables other than idt_table technically do not need to be page > > >> aligned, at least not at the current time, but using a common > > >> declaration avoids mistakes. On 64 bits the table is exactly one page > > >> long, anyway. > > >> > > >> Signed-off-by: Kees Cook <keescook@chromium.org> > > >> Link: http://lkml.kernel.org/r/20130716183441.GA14232@www.outflux.net > > >> Reported-by: PaX Team <pageexec@gmail.com> > > >> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> > > >> --- > > >> arch/x86/kernel/head_64.S | 15 --------------- > > >> arch/x86/kernel/tracepoint.c | 6 ++---- > > >> arch/x86/kernel/traps.c | 12 ++++++------ > > >> 3 files changed, 8 insertions(+), 25 deletions(-) > > > > > > This patch is now in Linus's tree. Kees, did you also want this in the > > > -stable tree(s)? > > > > The potential problem was introduced with > > 4eefbe792baedb474e256d35370849992fcf1c79, so 3.10 needs it, yes. I had > > also sent a much smaller version here: > > http://git.kernel.org/cgit/linux/kernel/git/kees/linux.git/commit/?h=idt-stable&id=794c1e0df641e13050cfc4af340fc3c85bed4ea3 > > > > Either will address the problem. If there is no problem with taking > > the larger clean-up for stable, then that's probably easiest. > > I'd prefer to stick with what ended up in Linus's tree, so I'll just > queue this one up in a future stable 3.10 release, thanks. I ended up taking the smaller version, as this one doesn't apply to 3.10, you were right in the beginning :) thanks, greg k-h ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2013-08-01 7:31 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
[not found] <20130719011526.15FA46608B1@gitolite.kernel.org>
2013-07-19 1:30 ` x86: Make sure IDT is page aligned Greg KH
2013-07-19 1:36 ` Kees Cook
2013-07-19 1:50 ` Greg KH
2013-08-01 3:12 ` Greg KH
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox
Powered by JetHome