linux-kernel - [PATCH 4.4 114/160] mm: refuse wrapped vm

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Date:   Mon, 19 Nov 2018 17:29:13 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Hector Marco-Gisbert <hecmargi@....es>,
        Ismael Ripoll Ripoll <iripoll@....es>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Chen Gang <gang.chen.5i5j@...il.com>,
        Michal Hocko <mhocko@...e.com>,
        Konstantin Khlebnikov <koct9i@...il.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 114/160] mm: refuse wrapped vm_brk requests

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

commit ba093a6d9397da8eafcfbaa7d95bd34255da39a0 upstream.

The vm_brk() alignment calculations should refuse to overflow.  The ELF
loader depending on this, but it has been fixed now.  No other unsafe
callers have been found.

Link: http://lkml.kernel.org/r/1468014494-25291-3-git-send-email-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@...omium.org>
Reported-by: Hector Marco-Gisbert <hecmargi@....es>
Cc: Ismael Ripoll Ripoll <iripoll@....es>
Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Chen Gang <gang.chen.5i5j@...il.com>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Konstantin Khlebnikov <koct9i@...il.com>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
[bwh: Backported to 4.4: adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@...ethink.co.uk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 mm/mmap.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 39f5fbd07486..dd9205542a86 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2808,16 +2808,18 @@ static inline void verify_mm_writelocked(struct mm_struct *mm)
  *  anonymous maps.  eventually we may be able to do some
  *  brk-specific accounting here.
  */
-static unsigned long do_brk(unsigned long addr, unsigned long len)
+static unsigned long do_brk(unsigned long addr, unsigned long request)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma, *prev;
-	unsigned long flags;
+	unsigned long flags, len;
 	struct rb_node **rb_link, *rb_parent;
 	pgoff_t pgoff = addr >> PAGE_SHIFT;
 	int error;
 
-	len = PAGE_ALIGN(len);
+	len = PAGE_ALIGN(request);
+	if (len < request)
+		return -ENOMEM;
 	if (!len)
 		return addr;
 
-- 
2.17.1