Messages in this thread | | | Date | Tue, 21 Jul 2015 17:31:07 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/mm/pat: Do a small optimization in reserve_memtype |
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On Tue, Jul 21, 2015 at 03:32:50PM +0800, Pan Xinhui wrote: > yes, we may access an freed memory at that time. Because entry is > stored in rb-tree. Need lock when we access it.
Ah, we touch entry, right.
> > improve the comments over memtype_lock to explain what exactly it protects. > > > lock is needed when we access the data stored in rb-tree. :)
I didn't ask you what it protects - I can do my own grepping and read pat_rbtree.c just fine - I asked you to update the comment.
> I find another bug, although it's very hard to hit. > just in reserve_memtype() > ---------------------------------- > err = rbt_memtype_check_insert(new, new_type); > if (err) { > printk(KERN_INFO "reserve_memtype failed [mem %#010Lx-%#010Lx], track %s, req %s\n", > start, end - 1, > cattr_name(new->type), cattr_name(req_type)); > kfree(new); > spin_unlock(&memtype_lock); > > return err; > } > > spin_unlock(&memtype_lock); //this unlock may cause problems because the next dprintk access *new*
Yes.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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