"value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: IDLETIMER: Fix for possible ABBA deadlock\n\nDeletion of the last rule referencing a given idletimer may happen at\nthe same time as a read of its file in sysfs:\n\n| ======================================================\n| WARNING: possible circular locking dependency detected\n| 6.12.0-rc7-01692-g5e9a28f41134-dirty #594 Not tainted\n| ------------------------------------------------------\n| iptables/3303 is trying to acquire lock:\n| ffff8881057e04b8 (kn->active#48){++++}-{0:0}, at: __kernfs_remove+0x20\n|\n| but task is already holding lock:\n| ffffffffa0249068 (list_mutex){+.+.}-{3:3}, at: idletimer_tg_destroy_v]\n|\n| which lock already depends on the new lock.\n\nA simple reproducer is:\n\n| #!/bin/bash\n|\n| while true; do\n| iptables -A INPUT -i foo -j IDLETIMER --timeout 10 --label \"testme\"\n| iptables -D INPUT -i foo -j IDLETIMER --timeout 10 --label \"testme\"\n| done &\n| while true; do\n| cat /sys/class/xt_idletimer/timers/testme >/dev/null\n| done\n\nAvoid this by freeing list_mutex right after deleting the element from\nthe list, then continuing with the teardown."
