syzbot


KASAN: invalid-free in io_sqe_files_unregister

Status: fixed on 2019/12/13 00:31
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+3254bc44113ae1e331ee@syzkaller.appspotmail.com
Fix commit: 46568e9be70f io_uring: fix error clear of ->file_table in io_sqe_files_register()
First crash: 1682d, last: 1682d
Cause bisection: introduced by (bisect log) :
commit 65e19f54d29cd8559ce60cfd0d751bef7afbdc5c
Author: Jens Axboe <axboe@kernel.dk>
Date: Sat Oct 26 13:20:21 2019 +0000

  io_uring: support for larger fixed file sets

Crash: KASAN: invalid-free in io_sqe_files_unregister (log)
Repro: C syz .config
  
Discussions (2)
Title Replies (including bot) Last reply
[PATCH] io_uring: fix error clear of ->file_table in io_sqe_files_register() 6 (6) 2019/11/11 04:19
KASAN: invalid-free in io_sqe_files_unregister 1 (3) 2019/11/10 15:46

Sample crash report:
RBP: 0000000000000005 R08: 0000000000000001 R09: 00007ffd5b970032
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000401ef0
R13: 0000000000401f80 R14: 0000000000000000 R15: 0000000000000000
==================================================================
BUG: KASAN: double-free or invalid-free in io_sqe_files_unregister+0x20b/0x300 fs/io_uring.c:3185

CPU: 1 PID: 8819 Comm: syz-executor452 Not tainted 5.4.0-rc6-next-20191108 #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+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 kasan_report_invalid_free+0x65/0xa0 mm/kasan/report.c:468
 __kasan_slab_free+0x13a/0x150 mm/kasan/common.c:450
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 io_sqe_files_unregister+0x20b/0x300 fs/io_uring.c:3185
 io_ring_ctx_free fs/io_uring.c:3998 [inline]
 io_ring_ctx_wait_and_kill+0x348/0x700 fs/io_uring.c:4060
 io_uring_release+0x42/0x50 fs/io_uring.c:4068
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x904/0x2e60 kernel/exit.c:817
 do_group_exit+0x135/0x360 kernel/exit.c:921
 __do_sys_exit_group kernel/exit.c:932 [inline]
 __se_sys_exit_group kernel/exit.c:930 [inline]
 __x64_sys_exit_group+0x44/0x50 kernel/exit.c:930
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43f2c8
Code: 31 b8 c5 f7 ff ff 48 8b 5c 24 28 48 8b 6c 24 30 4c 8b 64 24 38 4c 8b 6c 24 40 4c 8b 74 24 48 4c 8b 7c 24 50 48 83 c4 58 c3 66 <0f> 1f 84 00 00 00 00 00 48 8d 35 59 ca 00 00 0f b6 d2 48 89 fb 48
RSP: 002b:00007ffd5b976008 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043f2c8
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004bf0a8 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 8819:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:510 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x163/0x770 mm/slab.c:3665
 kmalloc_array include/linux/slab.h:598 [inline]
 kcalloc include/linux/slab.h:609 [inline]
 io_sqe_files_register fs/io_uring.c:3373 [inline]
 __io_uring_register+0x11d4/0x3120 fs/io_uring.c:4474
 __do_sys_io_uring_register fs/io_uring.c:4526 [inline]
 __se_sys_io_uring_register fs/io_uring.c:4508 [inline]
 __x64_sys_io_uring_register+0x1a1/0x570 fs/io_uring.c:4508
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8819:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 io_sqe_files_register fs/io_uring.c:3379 [inline]
 __io_uring_register+0x13a7/0x3120 fs/io_uring.c:4474
 __do_sys_io_uring_register fs/io_uring.c:4526 [inline]
 __se_sys_io_uring_register fs/io_uring.c:4508 [inline]
 __x64_sys_io_uring_register+0x1a1/0x570 fs/io_uring.c:4508
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a7619140
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff8880a7619140, ffff8880a7619160)
The buggy address belongs to the page:
page:ffffea00029d8640 refcount:1 mapcount:0 mapping:ffff8880aa4001c0 index:0xffff8880a7619fc1
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00025b2488 ffffea0002975c88 ffff8880aa4001c0
raw: ffff8880a7619fc1 ffff8880a7619000 0000000100000024 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a7619000: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a7619080: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8880a7619100: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
                                           ^
 ffff8880a7619180: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a7619200: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/11/10 07:57 linux-next 5591cf003452 dc438b91 .config console log report syz C ci-upstream-linux-next-kasan-gce-root
2019/11/10 11:41 linux-next 5591cf003452 dc438b91 .config console log report ci-upstream-linux-next-kasan-gce-root
2019/11/10 07:36 linux-next 5591cf003452 dc438b91 .config console log report ci-upstream-linux-next-kasan-gce-root
* Struck through repros no longer work on HEAD.