On Tue, Feb 28, 2012 at 6:10 AM, Hugh Dickins <hughd@xxxxxxxxxx> wrote:
> On Tue, 28 Feb 2012, Ware, Ryan R wrote:
>> On Tue, Feb 28, 2012 at 7:46 AM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>wrote:
>> > On Fri, 24 Feb 2012 19:19:22 -0800 (PST)
>> > Hugh Dickins <hughd@xxxxxxxxxx> 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.
Yeah, that's how I understood it too. These the are places where
security_inode_init_security() is called:
- http://lxr.free-electrons.com/source/mm/shmem.c#L1459
- http://lxr.free-electrons.com/source/mm/shmem.c#L1590
>
> Hugh
/Jarkko
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. 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: <a href