f2fs: check memory boundary by insane namelen

If namelen is corrupted to have very long value, fill_dentries can copy
wrong memory area.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index bacc667950b6473e8c342d60a87803aeb0ac0d15..c0c845da12fa5cfa33f5953a0b5c7d847d48598a 100644 (file)
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -808,6 +808,17 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
                de_name.name = d->filename[bit_pos];
                de_name.len = le16_to_cpu(de->name_len);
 
+               /* check memory boundary before moving forward */
+               bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
+               if (unlikely(bit_pos > d->max)) {
+                       f2fs_msg(sbi->sb, KERN_WARNING,
+                               "%s: corrupted namelen=%d, run fsck to fix.",
+                               __func__, le16_to_cpu(de->name_len));
+                       set_sbi_flag(sbi, SBI_NEED_FSCK);
+                       err = -EINVAL;
+                       goto out;
+               }
+
                if (f2fs_encrypted_inode(d->inode)) {
                        int save_len = fstr->len;
 
@@ -830,7 +841,6 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
                if (readdir_ra)
                        f2fs_ra_node_page(sbi, le32_to_cpu(de->ino));
 
-               bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
                ctx->pos = start_pos + bit_pos;
        }
 out: