syzbot


KASAN: use-after-free Read in __fdget_raw

Status: closed as invalid on 2022/03/05 18:27
Reported-by: syzbot+569a9f38546d62a570d2@syzkaller.appspotmail.com
First crash: 819d, last: 819d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
Discussions (1)
Title Replies (including bot) Last reply
[REPORT] Use-after-free Read in __fdget_raw in v5.10.y 20 (20) 2022/05/19 12:13
Last patch testing requests (1)
Created Duration User Patch Repo Result
2022/02/18 22:03 8m tadeusz.struk@linaro.org https://android.googlesource.com/kernel/common android12-5.10 OK

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:27 [inline]
BUG: KASAN: use-after-free in __fget_light fs/file.c:903 [inline]
BUG: KASAN: use-after-free in __fdget_raw+0x57/0x1e0 fs/file.c:923
Read of size 4 at addr ffff88811d4d0000 by task io_wqe_worker-0/374

CPU: 1 PID: 374 Comm: io_wqe_worker-0 Not tainted 5.10.93-syzkaller-01028-g0347b1658399 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 print_address_description+0x8d/0x3d0 mm/kasan/report.c:233
 __kasan_report+0x142/0x220 mm/kasan/report.c:419
 kasan_report+0x51/0x70 mm/kasan/report.c:436
 check_region_inline mm/kasan/generic.c:135 [inline]
 kasan_check_range+0x2b6/0x2f0 mm/kasan/generic.c:186
 __kasan_check_read+0x11/0x20 mm/kasan/shadow.c:31
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 atomic_read include/asm-generic/atomic-instrumented.h:27 [inline]
 __fget_light fs/file.c:903 [inline]
 __fdget_raw+0x57/0x1e0 fs/file.c:923
 fdget_raw include/linux/file.h:70 [inline]
 path_init+0x6aa/0x1130 fs/namei.c:2347
 path_lookupat+0x2b/0x6c0 fs/namei.c:2403
 filename_lookup+0x23f/0x6c0 fs/namei.c:2446
 user_path_at_empty+0x40/0x50 fs/namei.c:2726
 user_path_at include/linux/namei.h:59 [inline]
 vfs_statx+0x10a/0x3f0 fs/stat.c:193
 do_statx+0xec/0x170 fs/stat.c:588
 io_statx fs/io_uring.c:4249 [inline]
 io_issue_sqe+0x2541/0xfc10 fs/io_uring.c:6086
 io_wq_submit_work+0x34c/0xf40 fs/io_uring.c:6155
 io_worker_handle_work+0x1558/0x1d90 fs/io-wq.c:573
 io_wqe_worker+0x39f/0xf20 fs/io-wq.c:615
 kthread+0x371/0x390 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Allocated by task 365:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:428 [inline]
 __kasan_slab_alloc+0xb2/0xe0 mm/kasan/common.c:461
 kasan_slab_alloc include/linux/kasan.h:259 [inline]
 slab_post_alloc_hook mm/slab.h:583 [inline]
 slab_alloc_node mm/slub.c:2954 [inline]
 slab_alloc mm/slub.c:2962 [inline]
 kmem_cache_alloc+0x1a2/0x380 mm/slub.c:2967
 dup_fd+0x71/0xc60 fs/file.c:293
 copy_files kernel/fork.c:1517 [inline]
 copy_process+0x12a6/0x5340 kernel/fork.c:2139
 kernel_clone+0x21f/0x9a0 kernel/fork.c:2513
 __do_sys_clone kernel/fork.c:2632 [inline]
 __se_sys_clone kernel/fork.c:2616 [inline]
 __x64_sys_clone+0x258/0x2d0 kernel/fork.c:2616
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 366:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:46
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:357
 ____kasan_slab_free+0x133/0x170 mm/kasan/common.c:360
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:368
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:1602 [inline]
 slab_free_freelist_hook+0xcc/0x1a0 mm/slub.c:1628
 slab_free mm/slub.c:3210 [inline]
 kmem_cache_free+0xb5/0x1f0 mm/slub.c:3226
 put_files_struct+0x318/0x350 fs/file.c:434
 exit_files+0x80/0xa0 fs/file.c:458
 do_exit+0x6d9/0x23a0 kernel/exit.c:808
 do_group_exit+0x16a/0x2d0 kernel/exit.c:910
 __do_sys_exit_group+0x17/0x20 kernel/exit.c:921
 __se_sys_exit_group+0x14/0x20 kernel/exit.c:919
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:919
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88811d4d0000
 which belongs to the cache files_cache of size 704
The buggy address is located 0 bytes inside of
 704-byte region [ffff88811d4d0000, ffff88811d4d02c0)
The buggy address belongs to the page:
page:ffffea0004753400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11d4d0
head:ffffea0004753400 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff888100066f00
raw: 0000000000000000 0000000080130013 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 357, ts 15953240908, free_ts 0
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2385 [inline]
 prep_new_page mm/page_alloc.c:2391 [inline]
 get_page_from_freelist+0xa74/0xa90 mm/page_alloc.c:4063
 __alloc_pages_nodemask+0x3c8/0x820 mm/page_alloc.c:5106
 alloc_slab_page mm/slub.c:1813 [inline]
 allocate_slab+0x6b/0x350 mm/slub.c:1815
 new_slab mm/slub.c:1876 [inline]
 new_slab_objects mm/slub.c:2635 [inline]
 ___slab_alloc+0x143/0x2f0 mm/slub.c:2798
 __slab_alloc mm/slub.c:2838 [inline]
 slab_alloc_node mm/slub.c:2920 [inline]
 slab_alloc mm/slub.c:2962 [inline]
 kmem_cache_alloc+0x26f/0x380 mm/slub.c:2967
 dup_fd+0x71/0xc60 fs/file.c:293
 copy_files kernel/fork.c:1517 [inline]
 copy_process+0x12a6/0x5340 kernel/fork.c:2139
 kernel_clone+0x21f/0x9a0 kernel/fork.c:2513
 __do_sys_clone kernel/fork.c:2632 [inline]
 __se_sys_clone kernel/fork.c:2616 [inline]
 __x64_sys_clone+0x258/0x2d0 kernel/fork.c:2616
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88811d4cff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88811d4cff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88811d4d0000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88811d4d0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811d4d0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
============================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/01/21 10:13 android12-5.10-lts 0347b1658399 ab3d9f17 .config console log report syz C ci2-android-5-10 KASAN: use-after-free Read in __fdget_raw
* Struck through repros no longer work on HEAD.