From adee5e7078c89b7b4171c6388db54f7e1384b3d4 Mon Sep 17 00:00:00 2001 From: Dietmar Maurer Date: Fri, 21 Oct 2016 15:34:48 +0200 Subject: [PATCH 1/1] fix CVE 2016-5195 --- CVE-2016-5195.patch | 92 +++++++++++++++++++++++++++++++++++++++++++++ Makefile | 3 +- changelog.Debian | 6 +++ 3 files changed, 100 insertions(+), 1 deletion(-) create mode 100644 CVE-2016-5195.patch diff --git a/CVE-2016-5195.patch b/CVE-2016-5195.patch new file mode 100644 index 0000000..0ade570 --- /dev/null +++ b/CVE-2016-5195.patch @@ -0,0 +1,92 @@ +From 19be0eaffa3ac7d8eb6784ad9bdbc7d67ed8e619 Mon Sep 17 00:00:00 2001 +From: Linus Torvalds +Date: Thu, 13 Oct 2016 13:07:36 -0700 +Subject: mm: remove gup_flags FOLL_WRITE games from __get_user_pages() + +This is an ancient bug that was actually attempted to be fixed once +(badly) by me eleven years ago in commit 4ceb5db9757a ("Fix +get_user_pages() race for write access") but that was then undone due to +problems on s390 by commit f33ea7f404e5 ("fix get_user_pages bug"). + +In the meantime, the s390 situation has long been fixed, and we can now +fix it by checking the pte_dirty() bit properly (and do it better). The +s390 dirty bit was implemented in abf09bed3cce ("s390/mm: implement +software dirty bits") which made it into v3.9. Earlier kernels will +have to look at the page state itself. + +Also, the VM has become more scalable, and what used a purely +theoretical race back then has become easier to trigger. + +To fix it, we introduce a new internal FOLL_COW flag to mark the "yes, +we already did a COW" rather than play racy games with FOLL_WRITE that +is very fundamental, and then use the pte dirty flag to validate that +the FOLL_COW flag is still valid. + +Reported-and-tested-by: Phil "not Paul" Oester +Acked-by: Hugh Dickins +Reviewed-by: Michal Hocko +Cc: Andy Lutomirski +Cc: Kees Cook +Cc: Oleg Nesterov +Cc: Willy Tarreau +Cc: Nick Piggin +Cc: Greg Thelen +Cc: stable@vger.kernel.org +Signed-off-by: Linus Torvalds +--- + include/linux/mm.h | 1 + + mm/memory.c | 15 +++++++++++++- + 2 files changed, 14 insertions(+), 2 deletions(-) + +diff --git a/include/linux/mm.h b/include/linux/mm.h +index e9caec6..ed85879 100644 +--- a/include/linux/mm.h ++++ b/include/linux/mm.h +@@ -1466,6 +1466,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma, + #define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */ + #define FOLL_NUMA 0x200 /* force NUMA hinting page fault */ + #define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */ ++#define FOLL_COW 0x4000 /* internal GUP flag */ + + typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr, + void *data); +diff --git a/mm/memory.c b/mm/memory.c +index b6e3037..2d8080c 100644 +--- a/mm/memory.c ++++ b/mm/memory.c +@@ -1296,6 +1296,17 @@ int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, + } + EXPORT_SYMBOL_GPL(zap_vma_ptes); + ++/* ++ * FOLL_FORCE can write to even unwritable pte's, but only ++ * after we've gone through a COW cycle and they are dirty. ++ */ ++static inline bool can_follow_write_pte(pte_t pte, unsigned int flags) ++{ ++ return pte_write(pte) || ++ ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte)); ++} ++ ++ + /* + * Do a quick page-table lookup for a single page. + */ +@@ -1385,7 +1396,7 @@ split_fallthrough: + migration_entry_wait(mm, pmd, address); + goto split_fallthrough; + } +- if ((flags & FOLL_WRITE) && !pte_write(pte)) ++ if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags)) + goto unlock; + + page = vm_normal_page(vma, address, pte); +@@ -1618,7 +1629,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, + */ + if ((ret & VM_FAULT_WRITE) && + !(vma->vm_flags & VM_WRITE)) +- foll_flags &= ~FOLL_WRITE; ++ foll_flags |= FOLL_COW; + + cond_resched(); + } diff --git a/Makefile b/Makefile index 189204a..7e79beb 100644 --- a/Makefile +++ b/Makefile @@ -1,7 +1,7 @@ RELEASE=3.4 KERNEL_VER=2.6.32 -PKGREL=179 +PKGREL=180 # also include firmware of previous versrion into # the fw package: fwlist-2.6.32-PREV-pve KREL=47 @@ -207,6 +207,7 @@ ${KERNEL_SRC}/README: ${KERNEL_SRC}.org/README cd ${KERNEL_SRC}; patch -p1 <../fix-idr-header-for-drbd-compilation.patch cd ${KERNEL_SRC}; patch -p1 <../kvm-x86-ignore-ioapic-polarity.patch cd ${KERNEL_SRC}; patch -p1 <../fix-jfs-compile-error.patch + cd ${KERNEL_SRC}; patch -p1 <../CVE-2016-5195.patch sed -i ${KERNEL_SRC}/Makefile -e 's/^EXTRAVERSION.*$$/EXTRAVERSION=${EXTRAVERSION}/' touch $@ diff --git a/changelog.Debian b/changelog.Debian index 5455834..1a2010d 100644 --- a/changelog.Debian +++ b/changelog.Debian @@ -1,3 +1,9 @@ +pve-kernel-2.6.32 (2.6.32-180) unstable; urgency=low + + * fix CVE 2016-5195 (CVE-2016-5195.patch) + + -- Proxmox Support Team Fri, 21 Oct 2016 15:34:26 +0200 + pve-kernel-2.6.32 (2.6.32-179) unstable; urgency=low * update to vzkernel-2.6.32-042stab117.16.src.rpm -- 2.39.5