From: Pavel Begunkov <asml.silence@gmail.com>
To: syzbot <syzbot+9c3492b27d10dc49ffa6@syzkaller.appspotmail.com>,
axboe@kernel.dk, io-uring@vger.kernel.org,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] KASAN: use-after-free Read in tctx_task_work (2)
Date: Thu, 19 Aug 2021 12:13:11 +0100 [thread overview]
Message-ID: <da19f91c-1257-e6b8-7fc7-7f852a489cd8@gmail.com> (raw)
In-Reply-To: <000000000000fc001d05c9e73a85@google.com>
On 8/19/21 11:44 AM, syzbot wrote:
> Hello,
>
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> KASAN: use-after-free Read in tctx_task_work
>
> ==================================================================
> BUG: KASAN: use-after-free in ctx_flush_and_put fs/io_uring.c:2002 [inline]
> BUG: KASAN: use-after-free in tctx_task_work+0x307/0x310 fs/io_uring.c:2049
> Read of size 4 at addr ffff888029d66358 by task syz-executor530/27775
#syz test: https://github.com/isilence/linux.git syztest_ctx_tw
>
> CPU: 0 PID: 27775 Comm: syz-executor530 Not tainted 5.14.0-rc5-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:105
> print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233
> __kasan_report mm/kasan/report.c:419 [inline]
> kasan_report.cold+0x83/0xdf mm/kasan/report.c:436
> ctx_flush_and_put fs/io_uring.c:2002 [inline]
> tctx_task_work+0x307/0x310 fs/io_uring.c:2049
> 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+0x125/0x310 kernel/exit.c:922
> get_signal+0x47f/0x2160 kernel/signal.c:2808
> 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+0x42/0xb0 arch/x86/entry/common.c:86
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x446729
> Code: Unable to access opcode bytes at RIP 0x4466ff.
> RSP: 002b:00007fada1a521e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
> RAX: 00000000000001d2 RBX: 00000000004cb458 RCX: 0000000000446729
> RDX: 0000000000000000 RSI: 0000000000006b46 RDI: 0000000000000006
> RBP: 00000000004cb450 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004cb45c
> R13: 00007ffff39bb49f R14: 00007fada1a52300 R15: 0000000000022000
>
> Allocated by task 27776:
> 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+0x9b/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:1206 [inline]
> io_uring_create fs/io_uring.c:9685 [inline]
> io_uring_setup+0x27d/0x2cf0 fs/io_uring.c:9791
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Freed by task 10491:
> 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+0xfb/0x130 mm/kasan/common.c:374
> kasan_slab_free include/linux/kasan.h:230 [inline]
> slab_free_hook mm/slub.c:1625 [inline]
> slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1650
> slab_free mm/slub.c:3210 [inline]
> kfree+0xe4/0x530 mm/slub.c:4264
> io_ring_ctx_free fs/io_uring.c:8712 [inline]
> io_ring_exit_work+0x13ba/0x1930 fs/io_uring.c:8861
> process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
> worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
> 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+0xe5/0x110 mm/kasan/generic.c:348
> insert_work+0x48/0x370 kernel/workqueue.c:1332
> __queue_work+0x5c1/0xed0 kernel/workqueue.c:1498
> queue_work_on+0xee/0x110 kernel/workqueue.c:1525
> queue_work include/linux/workqueue.h:507 [inline]
> io_ring_ctx_wait_and_kill+0x30a/0x3c0 fs/io_uring.c:8914
> io_uring_release+0x3e/0x50 fs/io_uring.c:8922
> __fput+0x288/0x920 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+0x125/0x310 kernel/exit.c:922
> get_signal+0x47f/0x2160 kernel/signal.c:2808
> 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+0x42/0xb0 arch/x86/entry/common.c:86
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Second to last potentially related work creation:
> kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
> kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
> insert_work+0x48/0x370 kernel/workqueue.c:1332
> __queue_work+0x5c1/0xed0 kernel/workqueue.c:1498
> queue_work_on+0xee/0x110 kernel/workqueue.c:1525
> queue_work include/linux/workqueue.h:507 [inline]
> io_ring_ctx_wait_and_kill+0x30a/0x3c0 fs/io_uring.c:8914
> io_uring_release+0x3e/0x50 fs/io_uring.c:8922
> __fput+0x288/0x920 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+0x125/0x310 kernel/exit.c:922
> get_signal+0x47f/0x2160 kernel/signal.c:2808
> 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+0x42/0xb0 arch/x86/entry/common.c:86
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> The buggy address belongs to the object at ffff888029d66000
> which belongs to the cache kmalloc-4k of size 4096
> The buggy address is located 856 bytes inside of
> 4096-byte region [ffff888029d66000, ffff888029d67000)
> The buggy address belongs to the page:
> page:ffffea0000a75800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29d60
> head:ffffea0000a75800 order:3 compound_mapcount:0 compound_pincount:0
> flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
> raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010842140
> 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 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6467, ts 58396905717, free_ts 57689976074
> prep_new_page mm/page_alloc.c:2436 [inline]
> get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4169
> __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5391
> alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2244
> alloc_slab_page mm/slub.c:1688 [inline]
> allocate_slab+0x32e/0x4b0 mm/slub.c:1828
> new_slab mm/slub.c:1891 [inline]
> new_slab_objects mm/slub.c:2637 [inline]
> ___slab_alloc+0x4ba/0x820 mm/slub.c:2800
> __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2840
> slab_alloc_node mm/slub.c:2922 [inline]
> slab_alloc mm/slub.c:2964 [inline]
> __kmalloc+0x312/0x330 mm/slub.c:4108
> kmalloc include/linux/slab.h:596 [inline]
> tomoyo_realpath_from_path+0xc3/0x620 security/tomoyo/realpath.c:254
> tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
> tomoyo_path_perm+0x21b/0x400 security/tomoyo/file.c:822
> security_inode_getattr+0xcf/0x140 security/security.c:1332
> vfs_getattr fs/stat.c:139 [inline]
> vfs_statx+0x164/0x390 fs/stat.c:207
> vfs_fstatat fs/stat.c:225 [inline]
> vfs_lstat include/linux/fs.h:3386 [inline]
> __do_sys_newlstat+0x91/0x110 fs/stat.c:380
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> page last free stack trace:
> reset_page_owner include/linux/page_owner.h:24 [inline]
> free_pages_prepare mm/page_alloc.c:1346 [inline]
> free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1397
> free_unref_page_prepare mm/page_alloc.c:3332 [inline]
> free_unref_page+0x19/0x690 mm/page_alloc.c:3411
> qlink_free mm/kasan/quarantine.c:146 [inline]
> qlist_free_all+0x5a/0xc0 mm/kasan/quarantine.c:165
> kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:272
> __kasan_slab_alloc+0x8e/0xa0 mm/kasan/common.c:444
> kasan_slab_alloc include/linux/kasan.h:254 [inline]
> slab_post_alloc_hook mm/slab.h:519 [inline]
> slab_alloc_node mm/slub.c:2956 [inline]
> slab_alloc mm/slub.c:2964 [inline]
> kmem_cache_alloc+0x285/0x4a0 mm/slub.c:2969
> getname_flags.part.0+0x50/0x4f0 fs/namei.c:138
> getname_flags include/linux/audit.h:319 [inline]
> getname+0x8e/0xd0 fs/namei.c:209
> do_sys_openat2+0xf5/0x420 fs/open.c:1198
> do_sys_open fs/open.c:1220 [inline]
> __do_sys_open fs/open.c:1228 [inline]
> __se_sys_open fs/open.c:1224 [inline]
> __x64_sys_open+0x119/0x1c0 fs/open.c:1224
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Memory state around the buggy address:
> ffff888029d66200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888029d66280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ffff888029d66300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffff888029d66380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888029d66400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> Tested on:
>
> commit: bdd748b6 io-wq: move nr_running and worker_refs out of..
> git tree: git://git.kernel.dk/linux-block for-5.15/io_uring
> console output: https://syzkaller.appspot.com/x/log.txt?x=13141b61300000
> kernel config: https://syzkaller.appspot.com/x/.config?x=cb4282936412304f
> 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
>
--
Pavel Begunkov
next prev parent reply other threads:[~2021-08-19 11:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-19 8:10 [syzbot] KASAN: use-after-free Read in tctx_task_work (2) syzbot
2021-08-19 10:03 ` Pavel Begunkov
2021-08-19 10:44 ` syzbot
2021-08-19 11:13 ` Pavel Begunkov [this message]
2021-08-19 17:25 ` syzbot
2021-08-19 20:56 ` Pavel Begunkov
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