On 02/21/2011 11:44 AM, Joel Becker wrote:
> On Mon, Feb 21, 2011 at 11:20:18AM +0100, Jiri Slaby wrote:
>> when configfs_attach_group fails in configfs_register_subsystem:
>> dentry = d_alloc(configfs_sb->s_root, &name);
>> if (dentry) {
>> d_add(dentry, NULL);
>>
>> err = configfs_attach_group(sd->s_element, &group->cg_item,
>> dentry);
>> if (err) {
>> d_delete(dentry);
>> dput(dentry);
>>
>>
>> d_delete kills the kernel. I don't know what the actual bug is here, but
>> d_delete looks broken anyway:
>> spin_lock(&dentry->d_lock);
>> inode = dentry->d_inode;
>> isdir = S_ISDIR(inode->i_mode); <======== dereference
>> if (dentry->d_count == 1) {
>> if (inode && !spin_trylock(&inode->i_lock)) {
>> ^^^^^ <============= test
>>
>> It seems like a superfluous test, not a potential null dereference to
>> me, right?
>
> I think you're right about the superfluous test, but I need more
> investigation to see what's going on. Thanks for the report.
> What was causing attach_group() to fail? Do you know?
Dunno, I just modprobe'd the configfs example from Doc dir
(configfs_example_macros).
regards,
--
js
suse labs
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