CVE-2022-50620

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> f2fs: fix to invalidate dcc-&gt;f2fs_issue_discard in error path<br /> <br /> Syzbot reports a NULL pointer dereference issue as below:<br /> <br /> __refcount_add include/linux/refcount.h:193 [inline]<br /> __refcount_inc include/linux/refcount.h:250 [inline]<br /> refcount_inc include/linux/refcount.h:267 [inline]<br /> get_task_struct include/linux/sched/task.h:110 [inline]<br /> kthread_stop+0x34/0x1c0 kernel/kthread.c:703<br /> f2fs_stop_discard_thread+0x3c/0x5c fs/f2fs/segment.c:1638<br /> kill_f2fs_super+0x5c/0x194 fs/f2fs/super.c:4522<br /> deactivate_locked_super+0x70/0xe8 fs/super.c:332<br /> deactivate_super+0xd0/0xd4 fs/super.c:363<br /> cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186<br /> __cleanup_mnt+0x20/0x30 fs/namespace.c:1193<br /> task_work_run+0xc4/0x14c kernel/task_work.c:177<br /> exit_task_work include/linux/task_work.h:38 [inline]<br /> do_exit+0x26c/0xbe0 kernel/exit.c:795<br /> do_group_exit+0x60/0xe8 kernel/exit.c:925<br /> __do_sys_exit_group kernel/exit.c:936 [inline]<br /> __se_sys_exit_group kernel/exit.c:934 [inline]<br /> __wake_up_parent+0x0/0x40 kernel/exit.c:934<br /> __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]<br /> invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]<br /> el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142<br /> do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206<br /> el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:636<br /> el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654<br /> el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581<br /> <br /> The root cause of this issue is in error path of f2fs_start_discard_thread(),<br /> it missed to invalidate dcc-&gt;f2fs_issue_discard, later kthread_stop() may<br /> access invalid pointer.