CVE-2022-50705

Описание

In the Linux kernel, the following vulnerability has been resolved: io_uring/rw: defer fsnotify calls to task context We can't call these off the kiocb completion as that might be off soft/hard irq context. Defer the calls to when we process the task_work for this request. That avoids valid complaints like: stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.0.0-rc6-syzkaller-00321-g105a36f3694e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_usage_bug kernel/locking/lockdep.c:3961 [inline] valid_state kernel/locking/lockdep.c:3973 [inline] mark_lock_irq kernel/locking/lockdep.c:4176 [inline] mark_lock.part.0.cold+0x18/0xd8 kernel/locking/lockdep.c:4632 mark_lock kernel/locking/lockdep.c:4596 [inline] mark_usage kernel/locking/lockdep.c:4527 [inline] __lock_acquire+0x11d9/0x56d0 kernel/locking/lockdep.c:5007 lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 __fs_reclaim_acquire mm/page_alloc.c:4674 [inline] fs_reclaim_acquire+0x115/0x160 mm/page_alloc.c:4688 might_alloc include/linux/sched/mm.h:271 [inline] slab_pre_alloc_hook mm/slab.h:700 [inline] slab_alloc mm/slab.c:3278 [inline] __kmem_cache_alloc_lru mm/slab.c:3471 [inline] kmem_cache_alloc+0x39/0x520 mm/slab.c:3491 fanotify_alloc_fid_event fs/notify/fanotify/fanotify.c:580 [inline] fanotify_alloc_event fs/notify/fanotify/fanotify.c:813 [inline] fanotify_handle_event+0x1130/0x3f40 fs/notify/fanotify/fanotify.c:948 send_to_group fs/notify/fsnotify.c:360 [inline] fsnotify+0xafb/0x1680 fs/notify/fsnotify.c:570 __fsnotify_parent+0x62f/0xa60 fs/notify/fsnotify.c:230 fsnotify_parent include/linux/fsnotify.h:77 [inline] fsnotify_file include/linux/fsnotify.h:99 [inline] fsnotify_access include/linux/fsnotify.h:309 [inline] __io_complete_rw_common+0x485/0x720 io_uring/rw.c:195 io_complete_rw+0x1a/0x1f0 io_uring/rw.c:228 iomap_dio_complete_work fs/iomap/direct-io.c:144 [inline] iomap_dio_bio_end_io+0x438/0x5e0 fs/iomap/direct-io.c:178 bio_endio+0x5f9/0x780 block/bio.c:1564 req_bio_endio block/blk-mq.c:695 [inline] blk_update_request+0x3fc/0x1300 block/blk-mq.c:825 scsi_end_request+0x7a/0x9a0 drivers/scsi/scsi_lib.c:541 scsi_io_completion+0x173/0x1f70 drivers/scsi/scsi_lib.c:971 scsi_complete+0x122/0x3b0 drivers/scsi/scsi_lib.c:1438 blk_complete_reqs+0xad/0xe0 block/blk-mq.c:1022 __do_softirq+0x1d3/0x9c6 kernel/softirq.c:571 invoke_softirq kernel/softirq.c:445 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:650 irq_exit_rcu+0x5/0x20 kernel/softirq.c:662 common_interrupt+0xa9/0xc0 arch/x86/kernel/irq.c:240

A locking context violation was found in the Linux kernel's io_uring subsystem. The fsnotify calls were being made directly from kiocb completion context, which can execute in soft or hard IRQ context. This causes lockdep warnings when fsnotify attempts memory allocation with GFP_KERNEL flags, which is not permitted in IRQ context. The fix defers fsnotify calls to task_work processing.