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From b40723891dca1d623c82ba1be8c4afa5c42da12d Mon Sep 17 00:00:00 2001
From: Yongli He <yongli.he@windriver.com>
Date: Mon, 25 Aug 2008 10:59:44 +0800
Subject: [PATCH 01/12] revoke special mmap handling V7 From: Pekka Enberg <penberg@cs.helsinki.fi>
This adds special handling for revoked shared memory mappings. We want to
raise SIGBUS if someone accesses a revoked mapping and return ENODEV if
somebody tries to remap one with mmap(2).
Cc: Alan Cox <alan@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Integrated-by: Yongli he <yongli.he@windriver.com>
---
include/linux/mm.h | 3 +++
mm/memory.c | 3 +++
mm/mmap.c | 12 ++++++++----
3 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 461baba..3d2019c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -111,6 +111,9 @@ extern unsigned int kobjsize(const void *objp);
#define VM_PAGEEXEC 0x80000000 /* vma->vm_page_prot needs special handling */
#endif
+#define VM_REVOKED 0x20000000 /* Mapping has been revoked */
+
+
#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
#endif
diff --git a/mm/memory.c b/mm/memory.c
index 2bf4fcd..b1e56ef 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3458,6 +3458,9 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
}
#endif
+ if (unlikely(vma->vm_flags & VM_REVOKED))
+ return VM_FAULT_SIGBUS;
+
pgd = pgd_offset(mm, address);
pud = pud_alloc(mm, pgd, address);
if (!pud)
diff --git a/mm/mmap.c b/mm/mmap.c
index 0ab80ae..1f8c0ac 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1315,11 +1315,15 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
/* Clear old maps */
error = -ENOMEM;
vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
- if (vma && vma->vm_start < addr + len) {
- if (do_munmap(mm, addr, len))
- return -ENOMEM;
- vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
+ if (vma) {
+ if (unlikely(vma->vm_flags & VM_REVOKED))
+ return -ENODEV;
+ if (vma->vm_start < addr + len) {
+ if (do_munmap(mm, addr, len))
+ return -ENOMEM;
+ vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
BUG_ON(vma && vma->vm_start < addr + len);
+ }
}
/* Check against address space limit. */
--
1.6.5.2
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