"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/l2tp: fix warning in l2tp_exit_net found by syzbot\n\nIn l2tp's net exit handler, we check that an IDR is empty before\ndestroying it:\n\n\tWARN_ON_ONCE(!idr_is_empty(&pn->l2tp_tunnel_idr));\n\tidr_destroy(&pn->l2tp_tunnel_idr);\n\nBy forcing memory allocation failures in idr_alloc_32, syzbot is able\nto provoke a condition where idr_is_empty returns false despite there\nbeing no items in the IDR. This turns out to be because the radix tree\nof the IDR contains only internal radix-tree nodes and it is this that\ncauses idr_is_empty to return false. The internal nodes are cleaned by\nidr_destroy.\n\nUse idr_for_each to check that the IDR is empty instead of\nidr_is_empty to avoid the problem."