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Tue, 13 Nov 2018 23:18:06 -0800 (PST) Date: Tue, 13 Nov 2018 23:18:06 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <00000000000057e614057a9abcd3@google.com> Subject: KASAN: null-ptr-deref Read in refcount_sub_and_test_checked (2) From: syzbot To: kyungmin.park@samsung.com, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, m.szyprowski@samsung.com, mchehab@kernel.org, pawel@osciak.com, 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 Hello, syzbot found the following crash on: HEAD commit: ccda4af0f4b9 Linux 4.20-rc2 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=16f9cb0b400000 kernel config: https://syzkaller.appspot.com/x/.config?x=4a0a89f12ca9b0f5 dashboard link: https://syzkaller.appspot.com/bug?extid=0468b73bdbb243217224 compiler: gcc (GCC) 8.0.1 20180413 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d20893400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=118f5a2b400000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+0468b73bdbb243217224@syzkaller.appspotmail.com ================================================================== BUG: KASAN: null-ptr-deref in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] BUG: KASAN: null-ptr-deref in refcount_sub_and_test_checked+0x9d/0x310 lib/refcount.c:179 Read of size 4 at addr 0000000000000020 by task syz-executor487/6051 CPU: 0 PID: 6051 Comm: syz-executor487 Not tainted 4.20.0-rc2+ #333 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+0x244/0x39d lib/dump_stack.c:113 kasan_report_error mm/kasan/report.c:352 [inline] kasan_report.cold.8+0x6d/0x309 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_read+0x11/0x20 mm/kasan/kasan.c:272 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] refcount_sub_and_test_checked+0x9d/0x310 lib/refcount.c:179 refcount_dec_and_test_checked+0x1a/0x20 lib/refcount.c:212 vb2_vmalloc_put+0x19/0x80 drivers/media/common/videobuf2/videobuf2-vmalloc.c:68 __vb2_buf_mem_free+0x112/0x210 drivers/media/common/videobuf2/videobuf2-core.c:242 __vb2_free_mem drivers/media/common/videobuf2/videobuf2-core.c:413 [inline] __vb2_queue_free+0x830/0xa30 drivers/media/common/videobuf2/videobuf2-core.c:458 vb2_core_queue_release+0x62/0x80 drivers/media/common/videobuf2/videobuf2-core.c:2231 vb2_queue_release drivers/media/common/videobuf2/videobuf2-v4l2.c:837 [inline] _vb2_fop_release+0x1d2/0x2b0 drivers/media/common/videobuf2/videobuf2-v4l2.c:1010 vb2_fop_release+0x77/0xc0 drivers/media/common/videobuf2/videobuf2-v4l2.c:1024 vivid_fop_release+0x18e/0x440 drivers/media/platform/vivid/vivid-core.c:474 v4l2_release+0x224/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:456 __fput+0x385/0xa30 fs/file_table.c:278 ____fput+0x15/0x20 fs/file_table.c:309 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1ad6/0x26d0 kernel/exit.c:867 do_group_exit+0x177/0x440 kernel/exit.c:970 __do_sys_exit_group kernel/exit.c:981 [inline] __se_sys_exit_group kernel/exit.c:979 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:979 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x442c78 Code: Bad RIP value. RSP: 002b:00007fff4ac5a278 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000442c78 RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 RBP: 00000000004c2848 R08: 00000000000000e7 R09: ffffffffffffffd0 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000006d4180 R14: 0000000000000000 R15: 0000000000000000 ================================================================== --- This bug 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 bug report. See: https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot. syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches