isofs: Fix unchecked printing of ER records

commit 4e2024624e678f0ebb916e6192bd23c1f9fdf696 upstream.

We didn't check length of rock ridge ER records before printing them.
Thus corrupted isofs image can cause us to access and print some memory
behind the buffer with obvious consequences.

Reported-and-tested-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/isofs/rock.c b/fs/isofs/rock.c
index bb63254ed8486f42200230b4bbaa80257f92700d..735d7522a3a911f19af593d6b5f7d366d6cf448d 100644 (file)
--- a/fs/isofs/rock.c
+++ b/fs/isofs/rock.c
@@ -362,6 +362,9 @@ repeat:
                        rs.cont_size = isonum_733(rr->u.CE.size);
                        break;
                case SIG('E', 'R'):
+                       /* Invalid length of ER tag id? */
+                       if (rr->u.ER.len_id + offsetof(struct rock_ridge, u.ER.data) > rr->len)
+                               goto out;
                        ISOFS_SB(inode->i_sb)->s_rock = 1;
                        printk(KERN_DEBUG "ISO 9660 Extensions: ");
                        {