romfs: fix romfs_get_unmapped_area() argument check

[linux-2.6-block.git] / fs / romfs / mmap-nommu.c

diff --git a/fs/romfs/mmap-nommu.c b/fs/romfs/mmap-nommu.c
index f0511e8169679fa3872938a2a9e0e9c19998049b..eed99428f1046d6a3dbd6191340d9d70e18b7ce0 100644 (file)
--- a/fs/romfs/mmap-nommu.c
+++ b/fs/romfs/mmap-nommu.c
@@ -27,14 +27,18 @@ static unsigned long romfs_get_unmapped_area(struct file *file,
 {
        struct inode *inode = file->f_mapping->host;
        struct mtd_info *mtd = inode->i_sb->s_mtd;
-       unsigned long isize, offset;
+       unsigned long isize, offset, maxpages, lpages;
 
        if (!mtd)
                goto cant_map_directly;
 
+       /* the mapping mustn't extend beyond the EOF */
+       lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
        isize = i_size_read(inode);
        offset = pgoff << PAGE_SHIFT;
-       if (offset > isize || len > isize || offset > isize - len)
+
+       maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
+       if ((pgoff >= maxpages) || (maxpages - pgoff < lpages))
                return (unsigned long) -EINVAL;
 
        /* we need to call down to the MTD layer to do the actual mapping */