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([2620:10d:c092:600::2:478]) by smtp.gmail.com with ESMTPSA id l24-20020a1ced18000000b003d99da8d30asm25641195wmh.46.2023.01.12.02.38.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Jan 2023 02:38:48 -0800 (PST) Message-ID: <3f4c1d69-cca2-ee6a-55e0-95028cf739da@gmail.com> Date: Thu, 12 Jan 2023 10:37:20 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.1 Subject: Re: [syzbot] KASAN: use-after-free Read in io_fallback_req_func To: syzbot , axboe@kernel.dk, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com References: <000000000000cf0f4905f20e504c@google.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <000000000000cf0f4905f20e504c@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 1/12/23 10:09, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 0a093b2893c7 Add linux-next specific files for 20230112 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=103269ce480000 > kernel config: https://syzkaller.appspot.com/x/.config?x=835f3591019836d5 > dashboard link: https://syzkaller.appspot.com/bug?extid=bc022c162e3b001bf607 > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > Unfortunately, I don't have any reproducer for this issue yet. #syz test: git://git.kernel.dk/linux.git syztest > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/8111a570d6cb/disk-0a093b28.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/ecc135b7fc9a/vmlinux-0a093b28.xz > kernel image: https://storage.googleapis.com/syzbot-assets/ca8d73b446ea/bzImage-0a093b28.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+bc022c162e3b001bf607@syzkaller.appspotmail.com > > ================================================================== > BUG: KASAN: use-after-free in io_fallback_req_func+0xc7/0x204 io_uring/io_uring.c:251 > Read of size 8 at addr ffff888070ac2e48 by task kworker/0:0/7 > > CPU: 0 PID: 7 Comm: kworker/0:0 Not tainted 6.2.0-rc3-next-20230112-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 > Workqueue: events io_fallback_req_func > Call Trace: > > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106 > print_address_description mm/kasan/report.c:306 [inline] > print_report+0x15e/0x45d mm/kasan/report.c:417 > kasan_report+0xc0/0xf0 mm/kasan/report.c:517 > io_fallback_req_func+0xc7/0x204 io_uring/io_uring.c:251 > process_one_work+0x9bf/0x1750 kernel/workqueue.c:2293 > worker_thread+0x669/0x1090 kernel/workqueue.c:2440 > kthread+0x2e8/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 > > > Allocated by task 7766: > kasan_save_stack+0x22/0x40 mm/kasan/common.c:45 > kasan_set_track+0x25/0x30 mm/kasan/common.c:52 > __kasan_slab_alloc+0x7f/0x90 mm/kasan/common.c:325 > kasan_slab_alloc include/linux/kasan.h:186 [inline] > slab_post_alloc_hook mm/slab.h:769 [inline] > kmem_cache_alloc_bulk+0x3aa/0x730 mm/slub.c:4033 > __io_alloc_req_refill+0xcc/0x40b io_uring/io_uring.c:1062 > io_alloc_req_refill io_uring/io_uring.h:348 [inline] > io_submit_sqes.cold+0x7c/0xc2 io_uring/io_uring.c:2407 > __do_sys_io_uring_enter+0x9e4/0x2c10 io_uring/io_uring.c:3429 > 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+0x63/0xcd > > Freed by task 5179: > kasan_save_stack+0x22/0x40 mm/kasan/common.c:45 > kasan_set_track+0x25/0x30 mm/kasan/common.c:52 > kasan_save_free_info+0x2e/0x40 mm/kasan/generic.c:518 > ____kasan_slab_free mm/kasan/common.c:236 [inline] > ____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200 > kasan_slab_free include/linux/kasan.h:162 [inline] > slab_free_hook mm/slub.c:1781 [inline] > slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1807 > slab_free mm/slub.c:3787 [inline] > kmem_cache_free+0xec/0x4e0 mm/slub.c:3809 > io_req_caches_free+0x1a9/0x1e6 io_uring/io_uring.c:2737 > io_ring_exit_work+0x2e7/0xc80 io_uring/io_uring.c:2967 > process_one_work+0x9bf/0x1750 kernel/workqueue.c:2293 > worker_thread+0x669/0x1090 kernel/workqueue.c:2440 > kthread+0x2e8/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 > > The buggy address belongs to the object at ffff888070ac2dc0 > which belongs to the cache io_kiocb of size 216 > The buggy address is located 136 bytes inside of > 216-byte region [ffff888070ac2dc0, ffff888070ac2e98) > > The buggy address belongs to the physical page: > page:ffffea0001c2b080 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x70ac2 > memcg:ffff88802a81d181 > flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) > raw: 00fff00000000200 ffff8881461d1780 dead000000000122 0000000000000000 > raw: 0000000000000000 00000000800c000c 00000001ffffffff ffff88802a81d181 > page dumped because: kasan: bad access detected > page_owner tracks the page as allocated > page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 5547, tgid 5545 (syz-executor.4), ts 182131630120, free_ts 181898498774 > prep_new_page mm/page_alloc.c:2549 [inline] > get_page_from_freelist+0x11bb/0x2d50 mm/page_alloc.c:4324 > __alloc_pages+0x1cb/0x5c0 mm/page_alloc.c:5590 > alloc_pages+0x1aa/0x270 mm/mempolicy.c:2281 > alloc_slab_page mm/slub.c:1851 [inline] > allocate_slab+0x25f/0x350 mm/slub.c:1998 > new_slab mm/slub.c:2051 [inline] > ___slab_alloc+0xa91/0x1400 mm/slub.c:3193 > __kmem_cache_alloc_bulk mm/slub.c:3951 [inline] > kmem_cache_alloc_bulk+0x23d/0x730 mm/slub.c:4026 > __io_alloc_req_refill+0xcc/0x40b io_uring/io_uring.c:1062 > io_alloc_req_refill io_uring/io_uring.h:348 [inline] > io_submit_sqes.cold+0x7c/0xc2 io_uring/io_uring.c:2407 > __do_sys_io_uring_enter+0x9e4/0x2c10 io_uring/io_uring.c:3429 > 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+0x63/0xcd > page last free stack trace: > reset_page_owner include/linux/page_owner.h:24 [inline] > free_pages_prepare mm/page_alloc.c:1451 [inline] > free_pcp_prepare+0x4d0/0x910 mm/page_alloc.c:1501 > free_unref_page_prepare mm/page_alloc.c:3387 [inline] > free_unref_page+0x1d/0x490 mm/page_alloc.c:3482 > qlink_free mm/kasan/quarantine.c:168 [inline] > qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187 > kasan_quarantine_reduce+0x192/0x220 mm/kasan/quarantine.c:294 > __kasan_slab_alloc+0x63/0x90 mm/kasan/common.c:302 > kasan_slab_alloc include/linux/kasan.h:186 [inline] > slab_post_alloc_hook mm/slab.h:769 [inline] > slab_alloc_node mm/slub.c:3452 [inline] > slab_alloc mm/slub.c:3460 [inline] > __kmem_cache_alloc_lru mm/slub.c:3467 [inline] > kmem_cache_alloc+0x175/0x320 mm/slub.c:3476 > kmem_cache_zalloc include/linux/slab.h:710 [inline] > taskstats_tgid_alloc kernel/taskstats.c:583 [inline] > taskstats_exit+0x5f3/0xb80 kernel/taskstats.c:622 > do_exit+0x822/0x2a90 kernel/exit.c:852 > do_group_exit+0xd4/0x2a0 kernel/exit.c:1012 > get_signal+0x225f/0x24f0 kernel/signal.c:2859 > arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306 > exit_to_user_mode_loop kernel/entry/common.c:168 [inline] > exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204 > __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] > syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297 > do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > Memory state around the buggy address: > ffff888070ac2d00: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc > ffff888070ac2d80: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb >> ffff888070ac2e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff888070ac2e80: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff888070ac2f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. -- Pavel Begunkov