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>
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/fs/isofs/rock.c b/fs/isofs/rock.c
index 69c737d4b517cf2d5e48f776aa2f5335fe46a57a..2ec72aeae9ca17f760b99070a98b724dd3e3108e 100644 (file)
--- a/fs/isofs/rock.c
+++ b/fs/isofs/rock.c
@@ -363,6 +363,9 @@ 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: ");
                        {