Messages in this thread | | | Date | Wed, 29 Apr 2015 03:36:13 +0100 | From | Al Viro <> | Subject | Re: [PATCH] Validate pointer when copying mount namespace. |
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On Wed, Apr 29, 2015 at 09:56:43AM +0800, Leon Ma wrote: > We encountered following panic. Validate the pointer to avoid this.
> @@ -2788,7 +2788,7 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, > q = next_mnt(q, new); > if (!q) > break; > - while (p->mnt.mnt_root != q->mnt.mnt_root) > + while (p && p->mnt.mnt_root != q->mnt.mnt_root) > p = next_mnt(p, old); > } > namespace_unlock();
Details, please. How do you reproduce that behaviour?
I don't like that loop in its current form (it relies upon _not_ encountering the same ->mnt_root in the parts of tree we hadn't copied), but your change doesn't make it any better. Seeing a reproducer would be useful in sorting it out; in this form the patch papers over the bug rather than fixing it.
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