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2002:a1c:10e:: with SMTP id 14mr13187526wmb.93.1629371622291; Thu, 19 Aug 2021 04:13:42 -0700 (PDT) Received: from [192.168.8.197] ([185.69.145.21]) by smtp.gmail.com with ESMTPSA id 7sm7715376wmk.39.2021.08.19.04.13.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 19 Aug 2021 04:13:41 -0700 (PDT) Subject: Re: [syzbot] KASAN: use-after-free Read in tctx_task_work (2) To: syzbot , axboe@kernel.dk, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com References: <000000000000fc001d05c9e73a85@google.com> From: Pavel Begunkov Message-ID: Date: Thu, 19 Aug 2021 12:13:11 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <000000000000fc001d05c9e73a85@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org 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