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Mon, 09 Jul 2018 19:16:01 -0700 (PDT) Date: Mon, 09 Jul 2018 19:16:01 -0700 In-Reply-To: <000000000000ccdf0605708a9ccc@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <00000000000028fe5e05709bb662@google.com> Subject: Re: KASAN: use-after-free Write in _free_event From: syzbot To: acme@kernel.org, alexander.shishkin@linux.intel.com, dvyukov@google.com, jolsa@redhat.com, linux-kernel@vger.kernel.org, mingo@redhat.com, namhyung@kernel.org, peterz@infradead.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org syzbot has found a reproducer for the following crash on: HEAD commit: 092150a25cb7 Merge branch 'for-linus' of git://git.kernel... git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=16627cc2400000 kernel config: https://syzkaller.appspot.com/x/.config?x=25856fac4e580aa7 dashboard link: https://syzkaller.appspot.com/bug?extid=a24c397a29ad22d86c98 compiler: gcc (GCC) 8.0.1 20180413 (experimental) syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=14d45afc400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16dd4968400000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+a24c397a29ad22d86c98@syzkaller.appspotmail.com ================================================================== BUG: KASAN: use-after-free in atomic_dec_and_test include/asm-generic/atomic-instrumented.h:222 [inline] BUG: KASAN: use-after-free in put_task_struct include/linux/sched/task.h:95 [inline] BUG: KASAN: use-after-free in _free_event+0x48d/0x1440 kernel/events/core.c:4451 Write of size 4 at addr ffff8801ab6360e0 by task syz-executor205/5237 CPU: 1 PID: 5237 Comm: syz-executor205 Not tainted 4.18.0-rc4+ #139 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+0x1c9/0x2b4 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278 atomic_dec_and_test include/asm-generic/atomic-instrumented.h:222 [inline] put_task_struct include/linux/sched/task.h:95 [inline] _free_event+0x48d/0x1440 kernel/events/core.c:4451 free_event+0xb4/0x180 kernel/events/core.c:4472 perf_event_release_kernel+0x7d5/0x1050 kernel/events/core.c:4633 perf_release+0x37/0x50 kernel/events/core.c:4647 __fput+0x355/0x8b0 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1b08/0x2750 kernel/exit.c:865 do_group_exit+0x177/0x440 kernel/exit.c:968 get_signal+0x88e/0x1970 kernel/signal.c:2468 do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x2e0/0x370 arch/x86/entry/common.c:162 prepare_exit_to_usermode+0x342/0x3b0 arch/x86/entry/common.c:197 retint_user+0x8/0x18 RIP: 0033: (null) Code: Bad RIP value. RSP: 002b:0000000020000048 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 00000000006dbc24 RCX: 0000000000445d89 RDX: 0000000020000100 RSI: 0000000020000040 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000020000080 R09: 0000000000000000 R10: 0000000020000000 R11: 0000000000000246 R12: 00000000006dbc20 R13: 0030656c69662f2e R14: 0000004000008912 R15: 0000000000000006 Allocated by task 5236: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc_node+0x144/0x780 mm/slab.c:3644 alloc_task_struct_node kernel/fork.c:157 [inline] dup_task_struct kernel/fork.c:779 [inline] copy_process.part.39+0x16b5/0x7220 kernel/fork.c:1641 copy_process kernel/fork.c:1616 [inline] _do_fork+0x291/0x12a0 kernel/fork.c:2099 __do_sys_clone kernel/fork.c:2206 [inline] __se_sys_clone kernel/fork.c:2200 [inline] __x64_sys_clone+0xbf/0x150 kernel/fork.c:2200 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 5236: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kmem_cache_free+0x86/0x2d0 mm/slab.c:3756 free_task_struct kernel/fork.c:162 [inline] free_task+0x16e/0x1f0 kernel/fork.c:390 copy_process.part.39+0x15c9/0x7220 kernel/fork.c:2034 copy_process kernel/fork.c:1616 [inline] _do_fork+0x291/0x12a0 kernel/fork.c:2099 __do_sys_clone kernel/fork.c:2206 [inline] __se_sys_clone kernel/fork.c:2200 [inline] __x64_sys_clone+0xbf/0x150 kernel/fork.c:2200 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8801ab6360c0 which belongs to the cache task_struct of size 5952 The buggy address is located 32 bytes inside of 5952-byte region [ffff8801ab6360c0, ffff8801ab637800) The buggy address belongs to the page: page:ffffea0006ad8d80 count:1 mapcount:0 mapping:ffff8801da94b200 index:0x0 compound_mapcount: 0 flags: 0x2fffc0000008100(slab|head) raw: 02fffc0000008100 ffffea0006ad9008 ffffea00075f5888 ffff8801da94b200 raw: 0000000000000000 ffff8801ab6360c0 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801ab635f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801ab636000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff8801ab636080: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff8801ab636100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801ab636180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================