jfs: Fix uninit-value access of new_ea in ea_buffer

syzbot reports that lzo1x_1_do_compress is using uninit-value:

=====================================================
BUG: KMSAN: uninit-value in lzo1x_1_do_compress+0x19f9/0x2510 lib/lzo/lzo1x_compress.c:178

...

Uninit was stored to memory at:
 ea_put fs/jfs/xattr.c:639 [inline]

...

Local variable ea_buf created at:
 __jfs_setxattr+0x5d/0x1ae0 fs/jfs/xattr.c:662
 __jfs_xattr_set+0xe6/0x1f0 fs/jfs/xattr.c:934

=====================================================

The reason is ea_buf->new_ea is not initialized properly.

Fix this by using memset to empty its content at the beginning
in ea_get().

Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=02341e0daa42a15ce130
Signed-off-by: Zhao Mengmeng <[email protected]>
Signed-off-by: Dave Kleikamp <[email protected]>

Author: Zhao Mengmeng

fs/jfs/xattr.c

@@ -434,6 +434,8 @@ static int ea_get(struct inode *inode, struct ea_buffer *ea_buf, int min_size)
 	int rc;
 	int quota_allocation = 0;
 
+	memset(&ea_buf->new_ea, 0, sizeof(ea_buf->new_ea));
+
 	/* When fsck.jfs clears a bad ea, it doesn't clear the size */
 	if (ji->ea.flag == 0)
 		ea_size = 0;