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Thu, 13 Feb 2020 08:57:12 -0800 (PST) Date: Thu, 13 Feb 2020 08:57:12 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000fb6fa1059e77fa6e@google.com> Subject: KASAN: null-ptr-deref Read in do_con_write From: syzbot To: b.zolnierkie@samsung.com, daniel.vetter@ffwll.ch, ghalat@redhat.com, gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, lukas@wunner.de, okash.khawaja@gmail.com, sam@ravnborg.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" 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: f2850dd5 Merge tag 'kbuild-fixes-v5.6' of git://git.kernel.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=122f97a5e00000 kernel config: https://syzkaller.appspot.com/x/.config?x=6780df5a5f208964 dashboard link: https://syzkaller.appspot.com/bug?extid=4b25dd89f2c5d49296d2 compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17b29701e00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11c8fc09e00000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+4b25dd89f2c5d49296d2@syzkaller.appspotmail.com ================================================================== BUG: KASAN: null-ptr-deref in scr_memcpyw include/linux/vt_buffer.h:49 [inline] BUG: KASAN: null-ptr-deref in delete_char drivers/tty/vt/vt.c:852 [inline] BUG: KASAN: null-ptr-deref in csi_P drivers/tty/vt/vt.c:1985 [inline] BUG: KASAN: null-ptr-deref in do_con_trol drivers/tty/vt/vt.c:2379 [inline] BUG: KASAN: null-ptr-deref in do_con_write+0x94d2/0xf360 drivers/tty/vt/vt.c:2797 Read of size 4294967294 at addr 0000000000000012 by task syz-executor662/8804 CPU: 0 PID: 8804 Comm: syz-executor662 Not tainted 5.6.0-rc1-syzkaller #0 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+0x1fb/0x318 lib/dump_stack.c:118 __kasan_report+0x167/0x1c0 mm/kasan/report.c:510 kasan_report+0x26/0x50 mm/kasan/common.c:641 check_memory_region_inline mm/kasan/generic.c:182 [inline] check_memory_region+0x2b6/0x2f0 mm/kasan/generic.c:192 memcpy+0x28/0x60 mm/kasan/common.c:127 scr_memcpyw include/linux/vt_buffer.h:49 [inline] delete_char drivers/tty/vt/vt.c:852 [inline] csi_P drivers/tty/vt/vt.c:1985 [inline] do_con_trol drivers/tty/vt/vt.c:2379 [inline] do_con_write+0x94d2/0xf360 drivers/tty/vt/vt.c:2797 con_write+0x25/0x40 drivers/tty/vt/vt.c:3135 process_output_block drivers/tty/n_tty.c:595 [inline] n_tty_write+0xd0c/0x1200 drivers/tty/n_tty.c:2333 do_tty_write drivers/tty/tty_io.c:962 [inline] tty_write+0x5a1/0x950 drivers/tty/tty_io.c:1046 __vfs_write+0xb8/0x740 fs/read_write.c:494 vfs_write+0x270/0x580 fs/read_write.c:558 ksys_write+0x117/0x220 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:620 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4404f9 Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b 14 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fffb1720718 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004404f9 RDX: 0000000000000078 RSI: 0000000020000140 RDI: 0000000000000004 RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401de0 R13: 0000000000401e70 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#status for how to communicate with syzbot. syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches