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authorDan Williams <dan.j.williams@intel.com>2017-03-10 03:16:42 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-03-10 04:01:09 +0300
commitef947b2529f918d9606533eb9c32b187ed6a5ede (patch)
tree802fbd6d597c8ab9ae1f2a989a61aa692117502c /arch
parentd19469e8415813cceaa494b6f538e327b9a95f3b (diff)
downloadlinux-ef947b2529f918d9606533eb9c32b187ed6a5ede.tar.xz
x86, mm: fix gup_pte_range() vs DAX mappings
gup_pte_range() fails to check pte_allows_gup() before translating a DAX pte entry, pte_devmap(), to a page. This allows writes to read-only mappings, and bypasses the DAX cacheline dirty tracking due to missed 'mkwrite' faults. The gup_huge_pmd() path and the gup_huge_pud() path correctly check pte_allows_gup() before checking for _devmap() entries. Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings") Link: http://lkml.kernel.org/r/148804251312.36605.12665024794196605053.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reported-by: Dave Hansen <dave.hansen@linux.intel.com> Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Xiong Zhou <xzhou@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/mm/gup.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 99c7805a9693..9d32ee608807 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -120,6 +120,11 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
return 0;
}
+ if (!pte_allows_gup(pte_val(pte), write)) {
+ pte_unmap(ptep);
+ return 0;
+ }
+
if (pte_devmap(pte)) {
pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
if (unlikely(!pgmap)) {
@@ -127,8 +132,7 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
pte_unmap(ptep);
return 0;
}
- } else if (!pte_allows_gup(pte_val(pte), write) ||
- pte_special(pte)) {
+ } else if (pte_special(pte)) {
pte_unmap(ptep);
return 0;
}