syzbot


KASAN: use-after-free Read in io_worker_get

Status: fixed on 2023/06/08 14:41
Subsystems: io-uring
[Documentation on labels]
Reported-by: syzbot+55cc59267340fad29512@syzkaller.appspotmail.com
Fix commit: e6db6f9398da io_uring/io-wq: only free worker if it was allocated for creation
First crash: 465d, last: 428d
Cause bisection: introduced by (bisect log) :
commit af82425c6a2d2f347c79b63ce74fca6dc6be157f
Author: Jens Axboe <axboe@kernel.dk>
Date: Mon Jan 2 23:49:46 2023 +0000

  io_uring/io-wq: free worker if task_work creation is canceled

Crash: KASAN: use-after-free Read in io_wq_worker_running (log)
Repro: C syz .config
  
Fix bisection: fixed by (bisect log) :
commit e6db6f9398dadcbc06318a133d4c44a2d3844e61
Author: Jens Axboe <axboe@kernel.dk>
Date: Sun Jan 8 17:39:17 2023 +0000

  io_uring/io-wq: only free worker if it was allocated for creation

  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] KASAN: use-after-free Read in io_worker_get 2 (5) 2023/03/15 12:17
Last patch testing requests (1)
Created Duration User Patch Repo Result
2023/01/09 13:09 21m asml.silence@gmail.com git://git.kernel.dk/linux.git syztest OK log
Fix bisection attempts (2)
Created Duration User Patch Repo Result
2023/03/14 23:53 5h40m bisect fix upstream job log (1)
2023/02/12 19:11 32m bisect fix upstream job log (0) log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:72 [inline]
BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:147 [inline]
BUG: KASAN: use-after-free in __refcount_add_not_zero include/linux/refcount.h:152 [inline]
BUG: KASAN: use-after-free in __refcount_inc_not_zero include/linux/refcount.h:227 [inline]
BUG: KASAN: use-after-free in refcount_inc_not_zero include/linux/refcount.h:245 [inline]
BUG: KASAN: use-after-free in io_worker_get+0x77/0x2a0 io_uring/io-wq.c:153
Read of size 4 at addr ffff888028085c00 by task syz-executor161/5058

CPU: 0 PID: 5058 Comm: syz-executor161 Not tainted 6.2.0-rc2-syzkaller-00256-ga689b938df39 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 print_address_description+0x74/0x340 mm/kasan/report.c:306
 print_report+0x107/0x220 mm/kasan/report.c:417
 kasan_report+0x139/0x170 mm/kasan/report.c:517
 kasan_check_range+0x2a7/0x2e0 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
 refcount_read include/linux/refcount.h:147 [inline]
 __refcount_add_not_zero include/linux/refcount.h:152 [inline]
 __refcount_inc_not_zero include/linux/refcount.h:227 [inline]
 refcount_inc_not_zero include/linux/refcount.h:245 [inline]
 io_worker_get+0x77/0x2a0 io_uring/io-wq.c:153
 io_wq_for_each_worker io_uring/io-wq.c:846 [inline]
 io_wq_exit_workers io_uring/io-wq.c:1250 [inline]
 io_wq_put_and_exit+0x2f8/0xcb0 io_uring/io-wq.c:1289
 io_uring_clean_tctx+0x164/0x1d0 io_uring/tctx.c:193
 io_uring_cancel_generic+0x60e/0x670 io_uring/io_uring.c:3145
 io_uring_files_cancel include/linux/io_uring.h:55 [inline]
 do_exit+0x2ad/0x2150 kernel/exit.c:822
 do_group_exit+0x1fd/0x2b0 kernel/exit.c:1012
 __do_sys_exit_group kernel/exit.c:1023 [inline]
 __se_sys_exit_group kernel/exit.c:1021 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1021
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f43fd8b3ce9
Code: 00 49 c7 c0 c0 ff ff ff be e7 00 00 00 ba 3c 00 00 00 eb 12 0f 1f 44 00 00 89 d0 0f 05 48 3d 00 f0 ff ff 77 1c f4 89 f0 0f 05 <48> 3d 00 f0 ff ff 76 e7 f7 d8 64 41 89 00 eb df 0f 1f 80 00 00 00
RSP: 002b:00007fffe594c5b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f43fd929350 RCX: 00007f43fd8b3ce9
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f43fd929350
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
 </TASK>

Allocated by task 5058:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4c/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:371 [inline]
 __kasan_kmalloc+0x97/0xb0 mm/kasan/common.c:380
 kmalloc_node include/linux/slab.h:606 [inline]
 kzalloc_node include/linux/slab.h:731 [inline]
 create_io_worker+0xef/0x630 io_uring/io-wq.c:801
 create_worker_cb+0x16b/0x330 io_uring/io-wq.c:339
 task_work_run+0x243/0x300 kernel/task_work.c:179
 get_signal+0x1654/0x1820 kernel/signal.c:2635
 arch_do_signal_or_restart+0x8d/0x5f0 arch/x86/kernel/signal.c:306
 exit_to_user_mode_loop+0x74/0x160 kernel/entry/common.c:168
 exit_to_user_mode_prepare+0xad/0x110 kernel/entry/common.c:203
 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:309
 exc_page_fault+0xa2/0x120 arch/x86/mm/fault.c:1578
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570

Freed by task 5058:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4c/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:518
 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1781 [inline]
 slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1807
 slab_free mm/slub.c:3787 [inline]
 __kmem_cache_free+0x71/0x110 mm/slub.c:3800
 io_wq_cancel_tw_create io_uring/io-wq.c:1233 [inline]
 io_wq_exit_workers io_uring/io-wq.c:1244 [inline]
 io_wq_put_and_exit+0x137/0xcb0 io_uring/io-wq.c:1289
 io_uring_clean_tctx+0x164/0x1d0 io_uring/tctx.c:193
 io_uring_cancel_generic+0x60e/0x670 io_uring/io_uring.c:3145
 io_uring_files_cancel include/linux/io_uring.h:55 [inline]
 do_exit+0x2ad/0x2150 kernel/exit.c:822
 do_group_exit+0x1fd/0x2b0 kernel/exit.c:1012
 __do_sys_exit_group kernel/exit.c:1023 [inline]
 __se_sys_exit_group kernel/exit.c:1021 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1021
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Last potentially related work creation:
 kasan_save_stack+0x3b/0x60 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xb0/0xc0 mm/kasan/generic.c:488
 task_work_add+0x87/0x340 kernel/task_work.c:48
 io_queue_worker_create+0x1e2/0x430 io_uring/io-wq.c:373
 sched_submit_work kernel/sched/core.c:6597 [inline]
 schedule+0x63/0x190 kernel/sched/core.c:6628
 schedule_timeout+0xac/0x300 kernel/time/timer.c:2143
 wait_woken+0xca/0x1b0 kernel/sched/wait.c:463
 af_alg_wait_for_data+0x458/0x700 crypto/af_alg.c:904
 _skcipher_recvmsg crypto/algif_skcipher.c:65 [inline]
 skcipher_recvmsg+0x2d9/0xea0 crypto/algif_skcipher.c:157
 sock_recvmsg_nosec net/socket.c:995 [inline]
 sock_recvmsg net/socket.c:1013 [inline]
 sock_read_iter+0x3fa/0x530 net/socket.c:1086
 call_read_iter include/linux/fs.h:2183 [inline]
 io_iter_do_read io_uring/rw.c:643 [inline]
 io_read+0x4a8/0x1310 io_uring/rw.c:766
 io_issue_sqe+0x44e/0xcd0 io_uring/io_uring.c:1856
 io_wq_submit_work+0x44a/0x9c0 io_uring/io_uring.c:1932
 io_worker_handle_work+0x8e1/0xee0 io_uring/io-wq.c:587
 io_wqe_worker+0x36c/0xde0 io_uring/io-wq.c:632
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

The buggy address belongs to the object at ffff888028085c00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff888028085c00, ffff888028085e00)

The buggy address belongs to the physical page:
page:ffffea0000a02100 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28084
head:ffffea0000a02100 order:2 compound_mapcount:0 subpages_mapcount:0 compound_pincount:0
anon flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffff888012841c80 0000000000000000 dead000000000001
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 9757639976, free_ts 0
 prep_new_page mm/page_alloc.c:2531 [inline]
 get_page_from_freelist+0x72b/0x7a0 mm/page_alloc.c:4283
 __alloc_pages+0x259/0x560 mm/page_alloc.c:5549
 alloc_page_interleave+0x22/0x1c0 mm/mempolicy.c:2119
 alloc_slab_page+0xbd/0x190 mm/slub.c:1851
 allocate_slab+0x5e/0x3c0 mm/slub.c:1998
 new_slab mm/slub.c:2051 [inline]
 ___slab_alloc+0x7f4/0xeb0 mm/slub.c:3193
 __slab_alloc mm/slub.c:3292 [inline]
 __slab_alloc_node mm/slub.c:3345 [inline]
 slab_alloc_node mm/slub.c:3442 [inline]
 __kmem_cache_alloc_node+0x25b/0x340 mm/slub.c:3491
 kmalloc_trace+0x26/0x60 mm/slab_common.c:1062
 kmalloc include/linux/slab.h:580 [inline]
 kzalloc include/linux/slab.h:720 [inline]
 device_private_init drivers/base/core.c:3323 [inline]
 device_add+0xb6/0xf90 drivers/base/core.c:3373
 netdev_register_kobject+0x178/0x310 net/core/net-sysfs.c:2015
 register_netdevice+0x136c/0x1a30 net/core/dev.c:10045
 register_netdev+0x37/0x50 net/core/dev.c:10173
 rose_proto_init+0x197/0x7c0 net/rose/af_rose.c:1545
 do_one_initcall+0xbd/0x2c0 init/main.c:1306
 do_initcall_level+0x168/0x220 init/main.c:1379
 do_initcalls+0x43/0x90 init/main.c:1395
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888028085b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888028085b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888028085c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888028085c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888028085d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/01/07 10:56 upstream a689b938df39 1dac8c7a .config console log report syz C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: use-after-free Read in io_worker_get
2023/01/13 19:11 upstream d9fc1511728c 529798b0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: use-after-free Read in io_worker_get
2023/01/12 22:44 upstream e8f60cd7db24 96166539 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: use-after-free Read in io_worker_get
2023/01/10 01:57 upstream 5a41237ad1d4 1dac8c7a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: use-after-free Read in io_worker_get
2023/01/07 15:58 upstream a689b938df39 1dac8c7a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: use-after-free Read in io_worker_get
* Struck through repros no longer work on HEAD.