Messages in this thread |  | | Date | Thu, 27 Sep 2001 20:52:51 -0400 (EDT) | From | Alexander Viro <> | Subject | new^H^H^Himproved devfs races |
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Richard, your symlink-related race fixes do not fix anything.
Enter devfs_readlink() Let it sleep in copy_to_user() Have symlink unregistered ->registered is 0, ->refcount is 1, ->linkname points to link body Have symlink registered again (module had been unloaded, now attacker causes its reload) ->registered is checked. Looks OK. ->refcount is set to 1. ->linkname is set to _new_ link body copy_to_user() wakes up and finishes. devfs_readlink() decrements ->refcount to 0. devfs_readlink() does kfree() on ->linkname (new one) We are left with registered entry with zero refcount and linkname pointing nowhere.
Same scenario applies to other places of that kind.
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