From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx179.postini.com [74.125.245.179]) by kanga.kvack.org (Postfix) with SMTP id 403586B0092 for ; Mon, 27 Feb 2012 23:11:28 -0500 (EST) Received: by dadv6 with SMTP id v6so7134986dad.14 for ; Mon, 27 Feb 2012 20:11:27 -0800 (PST) Date: Mon, 27 Feb 2012 20:10:53 -0800 (PST) From: Hugh Dickins Subject: Re: [PATCH] tmpfs: security xattr setting on inode creation In-Reply-To: Message-ID: References: <1329990365-23779-1-git-send-email-jarkko.sakkinen@intel.com> <20120227144602.07f5ec33.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: "Ware, Ryan R" Cc: Andrew Morton , Jarkko Sakkinen , James Morris , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org On Tue, 28 Feb 2012, Ware, Ryan R wrote: > On Tue, Feb 28, 2012 at 7:46 AM, Andrew Morton wrote: > > On Fri, 24 Feb 2012 19:19:22 -0800 (PST) > > Hugh Dickins wrote: > >... > > > + if (!new_xattr->name) { > > > + kfree(new_xattr); > > > + return -ENOMEM; > > > + } > > > + > > > + memcpy(new_xattr->name, XATTR_SECURITY_PREFIX, > > > + XATTR_SECURITY_PREFIX_LEN); > > > + memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN, > > > + xattr->name, len); > > > + > > > + spin_lock(&info->lock); > > > + list_add(&new_xattr->list, &info->xattr_list); > > > + spin_unlock(&info->lock); > > > + } > > > + > > > + return 0; > > > +} > > > > So if there's a kmalloc failure partway through the array, we leave a > > partially xattrified inode in place. > > > > Are we sure this is OK? > > > > I'm guessing Jarkko can clean that up a bit. It wouldn't be a good idea to > leave inaccurate data structures laying around during failure cases. Andrew raises a good concern, but Jarkko got it just right and no change is needed: any xattrs already allocated are properly linked on info->xattr_list, then when security_inode_init_security() fails (with an error other than EOPNOTSUPP) the failing inode is iput(), which ends up in shmem_evict_inode(), which kfree()s those xattrs (and their names) on info->xattr_list. Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org