udf: Detect incorrect directory size

Detect when a directory entry is (possibly partially) beyond directory
size and return EIO in that case since it means the filesystem is
corrupted. Otherwise directory operations can further corrupt the
directory and possibly also oops the kernel.

CC: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
CC: stable@vger.kernel.org
Reported-and-tested-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/directory.c b/fs/udf/directory.c
index 0a98a23..3835f98 100644 (file)
--- a/fs/udf/directory.c
+++ b/fs/udf/directory.c
@@ -152,6 +152,9 @@ struct fileIdentDesc *udf_fileident_read(struct inode *dir, loff_t *nf_pos,
                               sizeof(struct fileIdentDesc));
                }
        }
+       /* Got last entry outside of dir size - fs is corrupted! */
+       if (*nf_pos > dir->i_size)
+               return NULL;
        return fi;
 }