1. 19 Jun, 2009 1 commit
    • Eric Paris's avatar
      inotify: inotify_destroy_mark_entry could get called twice · 528da3e9
      Eric Paris authored
      inotify_destroy_mark_entry could get called twice for the same mark since it
      is called directly in inotify_rm_watch and when the mark is being destroyed for
      another reason.  As an example assume that the file being watched was just
      deleted so inotify_destroy_mark_entry would get called from the path
      fsnotify_inoderemove() -> fsnotify_destroy_marks_by_inode() ->
      fsnotify_destroy_mark_entry() -> inotify_destroy_mark_entry().  If this
      happened at the same time as userspace tried to remove a watch via
      inotify_rm_watch we could attempt to remove the mark from the idr twice and
      could thus double dec the ref cnt and potentially could be in a use after
      free/double free situation.  The fix is to have inotify_rm_watch use the
      generic recursive safe fsnotify_destroy_mark_by_entry() so we are sure the
      inotify_destroy_mark_entry() function can only be called one.
      
      This patch also renames the function to inotify_ingored_remove_idr() so it is
      clear what is actually going on in the function.
      
      Hopefully this fixes:
      [   20.342058] idr_remove called for id=20 which is not allocated.
      [   20.348000] Pid: 1860, comm: udevd Not tainted 2.6.30-tip #1077
      [   20.353933] Call Trace:
      [   20.356410]  [<ffffffff811a82b7>] idr_remove+0x115/0x18f
      [   20.361737]  [<ffffffff8134259d>] ? _spin_lock+0x6d/0x75
      [   20.367061]  [<ffffffff8111640a>] ? inotify_destroy_mark_entry+0xa3/0xcf
      [   20.373771]  [<ffffffff8111641e>] inotify_destroy_mark_entry+0xb7/0xcf
      [   20.380306]  [<ffffffff81115913>] inotify_freeing_mark+0xe/0x10
      [   20.386238]  [<ffffffff8111410d>] fsnotify_destroy_mark_by_entry+0x143/0x170
      [   20.393293]  [<ffffffff811163a3>] inotify_destroy_mark_entry+0x3c/0xcf
      [   20.399829]  [<ffffffff811164d1>] sys_inotify_rm_watch+0x9b/0xc6
      [   20.405850]  [<ffffffff8100bcdb>] system_call_fastpath+0x16/0x1b
      Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarEric Paris <eparis@redhat.com>
      Tested-by: default avatarPeter Ziljlstra <peterz@infradead.org>
      528da3e9
  2. 18 Jun, 2009 39 commits