Message-ID: <000000000000e1a5d005c9e514ed@google.com>
Date:   Thu, 19 Aug 2021 01:10:18 -0700
From:   syzbot <syzbot+9c3492b27d10dc49ffa6@...kaller.appspotmail.com>
To:     asml.silence@...il.com, axboe@...nel.dk, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] KASAN: use-after-free Read in tctx_task_work (2)

Hello,

syzbot found the following issue on:

HEAD commit:    f26c3abc432a Add linux-next specific files for 20210818
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=169f1731300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d472f8be79a62b44
dashboard link: https://syzkaller.appspot.com/bug?extid=9c3492b27d10dc49ffa6
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15f35e16300000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=161c1765300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9c3492b27d10dc49ffa6@...kaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in ctx_flush_and_put fs/io_uring.c:2031 [inline]
BUG: KASAN: use-after-free in tctx_task_work+0x307/0x310 fs/io_uring.c:2078
Read of size 4 at addr ffff88801da62358 by task syz-executor959/7251

CPU: 0 PID: 7251 Comm: syz-executor959 Not tainted 5.14.0-rc6-next-20210818-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:256
 __kasan_report mm/kasan/report.c:442 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
 ctx_flush_and_put fs/io_uring.c:2031 [inline]
 tctx_task_work+0x307/0x310 fs/io_uring.c:2078
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0xbae/0x2a30 kernel/exit.c:825
 do_group_exit+0x129/0x310 kernel/exit.c:922
 get_signal+0x482/0x2170 kernel/signal.c:2846
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x446749
Code: Unable to access opcode bytes at RIP 0x44671f.
RSP: 002b:00007f2e177871e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: 000000000000039b RBX: 00000000004cb468 RCX: 0000000000446749
RDX: 0000000000000000 RSI: 0000000000006b46 RDI: 0000000000000006
RBP: 00000000004cb460 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004cb46c
R13: 00007ffe292df50f R14: 00007f2e17787300 R15: 0000000000022000

Allocated by task 7251:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 ____kasan_kmalloc mm/kasan/common.c:472 [inline]
 __kasan_kmalloc+0x9f/0xd0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:591 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 io_ring_ctx_alloc fs/io_uring.c:1235 [inline]
 io_uring_create fs/io_uring.c:9876 [inline]
 io_uring_setup+0x27d/0x2d00 fs/io_uring.c:9982
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 6731:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0xff/0x140 mm/kasan/common.c:374
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1681 [inline]
 slab_free_freelist_hook+0x82/0x190 mm/slub.c:1706
 slab_free mm/slub.c:3463 [inline]
 kfree+0xea/0x540 mm/slub.c:4523
 io_ring_ctx_free fs/io_uring.c:8902 [inline]
 io_ring_exit_work+0x13c7/0x1940 fs/io_uring.c:9051
 process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297
 worker_thread+0x65b/0x1200 kernel/workqueue.c:2444
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe9/0x110 mm/kasan/generic.c:348
 insert_work+0x48/0x370 kernel/workqueue.c:1353
 __queue_work+0x5d1/0xf30 kernel/workqueue.c:1519
 queue_work_on+0xf6/0x110 kernel/workqueue.c:1546
 queue_work include/linux/workqueue.h:502 [inline]
 io_ring_ctx_wait_and_kill+0x314/0x3d0 fs/io_uring.c:9104
 io_uring_release+0x3e/0x50 fs/io_uring.c:9112
 __fput+0x288/0x9f0 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0xbae/0x2a30 kernel/exit.c:825
 do_group_exit+0x129/0x310 kernel/exit.c:922
 get_signal+0x482/0x2170 kernel/signal.c:2846
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88801da62000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 856 bytes inside of
 4096-byte region [ffff88801da62000, ffff88801da63000)
The buggy address belongs to the page:
page:ffffea0000769800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1da60
head:ffffea0000769800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010c42140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 254, ts 8722226076, free_ts 8721850730
 prep_new_page mm/page_alloc.c:2424 [inline]
 get_page_from_freelist+0xa76/0x2f90 mm/page_alloc.c:4151
 __alloc_pages+0x1ba/0x510 mm/page_alloc.c:5373
 alloc_pages+0x1a7/0x300 mm/mempolicy.c:2188
 alloc_slab_page mm/slub.c:1744 [inline]
 allocate_slab mm/slub.c:1881 [inline]
 new_slab+0x321/0x490 mm/slub.c:1944
 ___slab_alloc+0x90b/0xfb0 mm/slub.c:2974
 __slab_alloc.constprop.0+0x51/0xa0 mm/slub.c:3061
 slab_alloc_node mm/slub.c:3152 [inline]
 slab_alloc mm/slub.c:3194 [inline]
 kmem_cache_alloc_trace+0x30a/0x3c0 mm/slub.c:3211
 kmalloc include/linux/slab.h:591 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 kobject_uevent_env+0x240/0x1650 lib/kobject_uevent.c:524
 device_add+0xbc6/0x21b0 drivers/base/core.c:3340
 scsi_target_add drivers/scsi/scsi_sysfs.c:1309 [inline]
 scsi_sysfs_add_sdev+0x464/0x750 drivers/scsi/scsi_sysfs.c:1336
 scsi_sysfs_add_devices drivers/scsi/scsi_scan.c:1727 [inline]
 scsi_finish_async_scan drivers/scsi/scsi_scan.c:1812 [inline]
 do_scan_async+0x211/0x500 drivers/scsi/scsi_scan.c:1855
 async_run_entry_fn+0x9d/0x550 kernel/async.c:127
 process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297
 worker_thread+0x65b/0x1200 kernel/workqueue.c:2444
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1338 [inline]
 free_pcp_prepare+0x377/0x860 mm/page_alloc.c:1389
 free_unref_page_prepare mm/page_alloc.c:3315 [inline]
 free_unref_page+0x19/0x690 mm/page_alloc.c:3394
 sbitmap_free include/linux/sbitmap.h:165 [inline]
 scsi_device_dev_release_usercontext+0x65a/0xd60 drivers/scsi/scsi_sysfs.c:479
 execute_in_process_context+0x37/0x160 kernel/workqueue.c:3358
 device_release+0xa3/0x240 drivers/base/core.c:2195
 kobject_cleanup lib/kobject.c:705 [inline]
 kobject_release lib/kobject.c:736 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1d0/0x540 lib/kobject.c:753
 put_device+0x1b/0x30 drivers/base/core.c:3466
 __scsi_remove_device+0x1e1/0x3e0 drivers/scsi/scsi_sysfs.c:1477
 scsi_probe_and_add_lun+0x266d/0x35a0 drivers/scsi/scsi_scan.c:1205
 __scsi_scan_target+0x229/0xdc0 drivers/scsi/scsi_scan.c:1588
 scsi_scan_channel drivers/scsi/scsi_scan.c:1676 [inline]
 scsi_scan_channel+0x148/0x1e0 drivers/scsi/scsi_scan.c:1652
 scsi_scan_host_selected+0x2df/0x3b0 drivers/scsi/scsi_scan.c:1705
 do_scsi_scan_host+0x1eb/0x260 drivers/scsi/scsi_scan.c:1844
 do_scan_async+0x3e/0x500 drivers/scsi/scsi_scan.c:1854
 async_run_entry_fn+0x9d/0x550 kernel/async.c:127
 process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297

Memory state around the buggy address:
 ffff88801da62200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801da62280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88801da62300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff88801da62380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801da62400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This report is generated by a bot. It may contain errors.
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