jfs: Fix array-index-out-of-bounds in diFree

Reported-by: [e-mail]
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jeongjun Park <[e-mail]>
Signed-off-by: Dave Kleikamp <[e-mail]>

fs/jfs/jfs_imap.c

···
 int diRead(struct inode *ip)
 {
 	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
-	int iagno, ino, extno, rc;
+	int iagno, ino, extno, rc, agno;
 	struct inode *ipimap;
 	struct dinode *dp;
 	struct iag *iagp;
···
 
 	/* get the ag for the iag */
 	agstart = le64_to_cpu(iagp->agstart);
+	agno = BLKTOAG(agstart, JFS_SBI(ip->i_sb));
 
 	release_metapage(mp);
+	if (agno >= MAXAG || agno < 0)
+		return -EIO;
 
 	rel_inode = (ino & (INOSPERPAGE - 1));
 	pageno = blkno >> sbi->l2nbperpage;