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authorAwais Belal <awais_belal@mentor.com>2016-10-27 14:12:13 +0500
committerAwais Belal <awais_belal@mentor.com>2016-10-27 14:12:17 +0500
commitaa43ad3b167ca61050b2aa40e461d29e3fe6aed3 (patch)
treef6d819779f6a25ae7d98587132fe86ea807183c0 /common/recipes-kernel
parentd9b5c6a3cbb2f066c4403f2642df7c6d520b29a6 (diff)
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linux-yocto: fix CVE-2016-5195
This integrates the fix for CV-2016-5195 from upstream. Signed-off-by: Awais Belal <awais_belal@mentor.com>
Diffstat (limited to 'common/recipes-kernel')
-rw-r--r--common/recipes-kernel/linux/files/CVE-2016-5195.patch91
-rw-r--r--common/recipes-kernel/linux/files/linux-yocto-amd-patches.scc1
2 files changed, 92 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/files/CVE-2016-5195.patch b/common/recipes-kernel/linux/files/CVE-2016-5195.patch
new file mode 100644
index 00000000..6b9fa694
--- /dev/null
+++ b/common/recipes-kernel/linux/files/CVE-2016-5195.patch
@@ -0,0 +1,91 @@
+From 1294d355881cc5c3421d24fee512f16974addb6c Mon Sep 17 00:00:00 2001
+From: Linus Torvalds <torvalds@linux-foundation.org>
+Date: Thu, 13 Oct 2016 13:07:36 -0700
+Subject: 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>
+
+diff --git a/include/linux/mm.h b/include/linux/mm.h
+index cfebb74..f0ffa01 100644
+--- a/include/linux/mm.h
++++ b/include/linux/mm.h
+@@ -2112,6 +2112,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma,
+ #define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */
+ #define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */
+ #define FOLL_MLOCK 0x1000 /* lock present pages */
++#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 deafa2c..4b0b7e7 100644
+--- a/mm/gup.c
++++ b/mm/gup.c
+@@ -58,6 +58,16 @@ static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
+ return -EEXIST;
+ }
+
++/*
++ * 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)
+ {
+@@ -92,7 +102,7 @@ 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;
+ }
+@@ -352,7 +362,7 @@ 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;
+ }
+
+--
+cgit v0.10.2
diff --git a/common/recipes-kernel/linux/files/linux-yocto-amd-patches.scc b/common/recipes-kernel/linux/files/linux-yocto-amd-patches.scc
index 1d9f3647..f99c964c 100644
--- a/common/recipes-kernel/linux/files/linux-yocto-amd-patches.scc
+++ b/common/recipes-kernel/linux/files/linux-yocto-amd-patches.scc
@@ -1137,3 +1137,4 @@ patch 1135-ASoC-dwc-add-quirk-to-override-COMP_PARAM_1-register.patch
patch 1136-ALSA-Soc-RT286Codec-Modifications-to-ALSA-SOC-Audio.patch
patch 1137-drm-amdgpu-acp-fix-resume-on-CZ-systems-with-AZ-audi.patch
patch 0001-amdgpu-fix-various-compilation-issues.patch
+patch CVE-2016-5195.patch