futurile/guix-play
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

gnu: linux-libre@4.1: Add fix for CVE-2016-5195.

Browse Source 
* gnu/packages/patches/linux-libre-4.1-CVE-2016-5195.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/linux.scm (linux-libre-4.1): Add patch.
This commit is contained in:
Mark H Weaver 2016-10-22 00:24:51 -04:00
parent 64de7d1ceb
commit a861665b75
No known key found for this signature in database
GPG Key ID: 7CEF29847562C516
3 changed files with 104 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
gnu/local.mk
View File

@ -680,6 +680,7 @@ dist_patch_DATA = \
%D%/packages/patches/libxv-CVE-2016-5407.patch \
%D%/packages/patches/libxvmc-CVE-2016-7953.patch \
%D%/packages/patches/libxslt-generated-ids.patch \
%D%/packages/patches/linux-libre-4.1-CVE-2016-5195.patch \
%D%/packages/patches/lirc-localstatedir.patch \
%D%/packages/patches/llvm-for-extempore.patch \
%D%/packages/patches/lm-sensors-hwmon-attrs.patch \

5
gnu/packages/linux.scm
View File

@ -339,7 +339,10 @@ It has been modified to remove all non-free binary blobs.")
(make-linux-libre "4.1.34"
"0dajsb363p9lgga22ml8gp9k9lxd8mvrzxk9y3h9c6hpzfcmqdqr"
%intel-compatible-systems
#:configuration-file kernel-config))
#:configuration-file kernel-config
#:patches (list %boot-logo-patch
(search-patch
"linux-libre-4.1-CVE-2016-5195.patch"))))
;; Avoid rebuilding kernel variants when there is a minor version bump.
(define %linux-libre-version "4.8.3")

99
gnu/packages/patches/linux-libre-4.1-CVE-2016-5195.patch Normal file
View File

@ -0,0 +1,99 @@
Fix CVE-2016-5195, a.k.a. Dirty COW.
Backported to linux-libre-4.1.x by Mark H Weaver <mhw@netris.org>.
From 18652320ea99913c95e7130d654be7f1da6b694f Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 13 Oct 2016 13:07:36 -0700
Subject: [PATCH] mm: remove gup_flags FOLL_WRITE games from __get_user_pages()
commit 19be0eaffa3ac7d8eb6784ad9bdbc7d67ed8e619 upstream.
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 <kernel@linuxace.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/mm.h | 1 +
mm/gup.c | 14 ++++++++++++--
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6b85ec6..7cadf0a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2064,6 +2064,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma,
#define FOLL_NUMA 0x200 /* force NUMA hinting page fault */
#define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */
#define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */
+#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/gup.c b/mm/gup.c
index 6297f6b..e6de9e7 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -32,6 +32,16 @@ static struct page *no_page_table(struct vm_area_struct *vma,
return NULL;
}
+/*
+ * 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));
+}
+
static struct page *follow_page_pte(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmd, unsigned int flags)
{
@@ -66,7 +76,7 @@ retry:
}
if ((flags & FOLL_NUMA) && pte_protnone(pte))
goto no_page;
- if ((flags & FOLL_WRITE) && !pte_write(pte)) {
+ if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags)) {
pte_unmap_unlock(ptep, ptl);
return NULL;
}
@@ -315,7 +325,7 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
* reCOWed by userspace write).
*/
if ((ret & VM_FAULT_WRITE) && !(vma->vm_flags & VM_WRITE))
- *flags &= ~FOLL_WRITE;
+ *flags |= FOLL_COW;
return 0;
}
--
2.10.1