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Diffstat (limited to 'drivers/mtd/mtdchar.c')
-rw-r--r--drivers/mtd/mtdchar.c48
1 files changed, 42 insertions, 6 deletions
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index f2f482bec57..a6e74514e66 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -1123,6 +1123,33 @@ static unsigned long mtdchar_get_unmapped_area(struct file *file,
}
#endif
+static inline unsigned long get_vm_size(struct vm_area_struct *vma)
+{
+ return vma->vm_end - vma->vm_start;
+}
+
+static inline resource_size_t get_vm_offset(struct vm_area_struct *vma)
+{
+ return (resource_size_t) vma->vm_pgoff << PAGE_SHIFT;
+}
+
+/*
+ * Set a new vm offset.
+ *
+ * Verify that the incoming offset really works as a page offset,
+ * and that the offset and size fit in a resource_size_t.
+ */
+static inline int set_vm_offset(struct vm_area_struct *vma, resource_size_t off)
+{
+ pgoff_t pgoff = off >> PAGE_SHIFT;
+ if (off != (resource_size_t) pgoff << PAGE_SHIFT)
+ return -EINVAL;
+ if (off + get_vm_size(vma) - 1 < off)
+ return -EINVAL;
+ vma->vm_pgoff = pgoff;
+ return 0;
+}
+
/*
* set up a mapping for shared memory segments
*/
@@ -1132,20 +1159,29 @@ static int mtdchar_mmap(struct file *file, struct vm_area_struct *vma)
struct mtd_file_info *mfi = file->private_data;
struct mtd_info *mtd = mfi->mtd;
struct map_info *map = mtd->priv;
- unsigned long start;
- unsigned long off;
- u32 len;
+ resource_size_t start, off;
+ unsigned long len, vma_len;
if (mtd->type == MTD_RAM || mtd->type == MTD_ROM) {
- off = vma->vm_pgoff << PAGE_SHIFT;
+ off = get_vm_offset(vma);
start = map->phys;
len = PAGE_ALIGN((start & ~PAGE_MASK) + map->size);
start &= PAGE_MASK;
- if ((vma->vm_end - vma->vm_start + off) > len)
+ vma_len = get_vm_size(vma);
+
+ /* Overflow in off+len? */
+ if (vma_len + off < off)
+ return -EINVAL;
+ /* Does it fit in the mapping? */
+ if (vma_len + off > len)
return -EINVAL;
off += start;
- vma->vm_pgoff = off >> PAGE_SHIFT;
+ /* Did that overflow? */
+ if (off < start)
+ return -EINVAL;
+ if (set_vm_offset(vma, off) < 0)
+ return -EINVAL;
vma->vm_flags |= VM_IO | VM_RESERVED;
#ifdef pgprot_noncached