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: Zefan Li <lizefan@huawei.com>

diff --git a/fs/isofs/rock.c b/fs/isofs/rock.c
index 26859dea2c46bc6611decd37b4ae8782f80c386c..17809499c752defc0f20c973ce10ec1cc2cf1655 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: ");
                        {