isofs: Fix unchecked printing of ER records

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>
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/isofs/rock.c b/fs/isofs/rock.c
index bb63254ed848..735d7522a3a9 100644
--- 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: ");
                         {