Messages in this thread | | | Date | Wed, 14 Mar 2012 20:10:48 +0000 | From | Al Viro <> | Subject | Re: [PATCH] vfs namespace: Don't assume mount namespace has valid root |
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On Wed, Mar 14, 2012 at 04:58:30PM -0400, Sasha Levin wrote: > This patch fixes the assumption that a mnt namespace will always have a valid > root object.
It's not an assumption, it's an invariant that should hold unless you have run into a bug somewhere.
Instances of struct mnt_namespace should *all* come from alloc_mnt_ns(). There are only two callers - dup_mnt_namespace() and create_mnt_ns(). The latter will assign non-NULL vfsmount to ->root or die NULL pointer dereference in mnt->mnt_ns = new_ns; The former will either assign non-NULL to ->root or kfree() mnt_namespace before anyone can see it.
And nothing should modify ->root after that assignment for as long as the instance of struct mnt_namespace is allocated.
Mind explaining how have you managed to get mnt_namespace with NULL ->root passed to dup_mnt_ns()?
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