| Message ID | 20180921150553.21016-5-yu-cheng.yu@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Control Flow Enforcement: Branch Tracking, PTRACE | expand |
On Fri, Sep 21, 2018 at 08:05:48AM -0700, Yu-cheng Yu wrote: > The indirect branch tracking legacy bitmap takes a large address > space. This causes may_expand_vm() failure on the address limit > check. For a IBT-enabled task, add the bitmap size to the > address limit. > > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> > --- > arch/x86/include/uapi/asm/resource.h | 5 +++++ > include/uapi/asm-generic/resource.h | 3 +++ > mm/mmap.c | 12 +++++++++++- > 3 files changed, 19 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/uapi/asm/resource.h b/arch/x86/include/uapi/asm/resource.h > index 04bc4db8921b..0741b2a6101a 100644 > --- a/arch/x86/include/uapi/asm/resource.h > +++ b/arch/x86/include/uapi/asm/resource.h > @@ -1 +1,6 @@ > +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */ > +#ifdef CONFIG_X86_INTEL_CET > +#define rlimit_as_extra() current->thread.cet.ibt_bitmap_size > +#endif Does this really belong to UAPI? > + > #include <asm-generic/resource.h> > diff --git a/include/uapi/asm-generic/resource.h b/include/uapi/asm-generic/resource.h > index f12db7a0da64..8a7608a09700 100644 > --- a/include/uapi/asm-generic/resource.h > +++ b/include/uapi/asm-generic/resource.h > @@ -58,5 +58,8 @@ > # define RLIM_INFINITY (~0UL) > #endif > > +#ifndef rlimit_as_extra > +#define rlimit_as_extra() 0 > +#endif And this? > #endif /* _UAPI_ASM_GENERIC_RESOURCE_H */ > diff --git a/mm/mmap.c b/mm/mmap.c > index fa581ced3f56..397b8cb0b0af 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -3237,7 +3237,17 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, > */ > bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) > { > - if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) > + unsigned long as_limit = rlimit(RLIMIT_AS); > + unsigned long as_limit_plus = as_limit + rlimit_as_extra(); > + > + /* as_limit_plus overflowed */ > + if (as_limit_plus < as_limit) > + as_limit_plus = RLIM_INFINITY; > + > + if (as_limit_plus > as_limit) > + as_limit = as_limit_plus; > + > + if (mm->total_vm + npages > as_limit >> PAGE_SHIFT) I wonder, how realistic a scenario where a userspace application enables IBT, configures a huge prefetchable IO memory region (that just ignores bits of offset beyond 16, for example), and start repeatedly loading a legacy library there at different linear addresses. > return false; > > if (is_data_mapping(flags) && > -- > 2.17.1 >
diff --git a/arch/x86/include/uapi/asm/resource.h b/arch/x86/include/uapi/asm/resource.h index 04bc4db8921b..0741b2a6101a 100644 --- a/arch/x86/include/uapi/asm/resource.h +++ b/arch/x86/include/uapi/asm/resource.h @@ -1 +1,6 @@ +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */ +#ifdef CONFIG_X86_INTEL_CET +#define rlimit_as_extra() current->thread.cet.ibt_bitmap_size +#endif + #include <asm-generic/resource.h> diff --git a/include/uapi/asm-generic/resource.h b/include/uapi/asm-generic/resource.h index f12db7a0da64..8a7608a09700 100644 --- a/include/uapi/asm-generic/resource.h +++ b/include/uapi/asm-generic/resource.h @@ -58,5 +58,8 @@ # define RLIM_INFINITY (~0UL) #endif +#ifndef rlimit_as_extra +#define rlimit_as_extra() 0 +#endif #endif /* _UAPI_ASM_GENERIC_RESOURCE_H */ diff --git a/mm/mmap.c b/mm/mmap.c index fa581ced3f56..397b8cb0b0af 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3237,7 +3237,17 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, */ bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) { - if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) + unsigned long as_limit = rlimit(RLIMIT_AS); + unsigned long as_limit_plus = as_limit + rlimit_as_extra(); + + /* as_limit_plus overflowed */ + if (as_limit_plus < as_limit) + as_limit_plus = RLIM_INFINITY; + + if (as_limit_plus > as_limit) + as_limit = as_limit_plus; + + if (mm->total_vm + npages > as_limit >> PAGE_SHIFT) return false; if (is_data_mapping(flags) &&
The indirect branch tracking legacy bitmap takes a large address space. This causes may_expand_vm() failure on the address limit check. For a IBT-enabled task, add the bitmap size to the address limit. Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> --- arch/x86/include/uapi/asm/resource.h | 5 +++++ include/uapi/asm-generic/resource.h | 3 +++ mm/mmap.c | 12 +++++++++++- 3 files changed, 19 insertions(+), 1 deletion(-)