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SubjectRe: OOPS in configfs when doing d_delete
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?

Joel

--

Life's Little Instruction Book #444

"Never underestimate the power of a kind word or deed."

http://www.jlbec.org/
jlbec@evilplan.org


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