From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.4 required=3.0 tests=FROM_LOCAL_HEX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7B8BC3A589 for ; Tue, 20 Aug 2019 22:58:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A7FF20C01 for ; Tue, 20 Aug 2019 22:58:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726203AbfHTW6H (ORCPT ); Tue, 20 Aug 2019 18:58:07 -0400 Received: from mail-io1-f70.google.com ([209.85.166.70]:36685 "EHLO mail-io1-f70.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726166AbfHTW6H (ORCPT ); Tue, 20 Aug 2019 18:58:07 -0400 Received: by mail-io1-f70.google.com with SMTP id i6so500595ioi.3 for ; Tue, 20 Aug 2019 15:58:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:message-id:subject:from:to; bh=96tDGWwwRLUJuc8ZLUttwZP0NNSrENPZkHRRK+Wfi44=; b=ABRt7ECqV6l5aytk6uLIzkT1b2t1/6Iw/v2369boVq/tvQzVvLD9PpL9qd9rKoMgk7 OnuGqJC0AIKHE9nRa2wqGadYRQ+WB760LoyRtMhIXhwOXNFUkakYIWStS+HYv7P8PrMS nOfqinAzJENLFK8ZjeLy1Iaqm0GVZYM+96nekMjJ3D6GdNsNbClD7T95yHnY5IG10tqo BwCnwnuS6+1vZqaIySlF57FpQKkdlEhifdiLMy7NFd0pPIFSb/2wi9sqpJM7JnqFm3l1 raDLSO4HHBqV06o47lBr5zrh8sCMGe0SjxHWJtGuR13LD6wzwZ4jCr/tmDruG8rkihrl GYQA== X-Gm-Message-State: APjAAAVMmEQTPRXbhhqg9q2bxWz3wGU5k7uXWZ7UUxi62VurnsUSirul DvrS4+4VN5zdi8izN0XjrqdeZ1G1RfqJmwq91XyBaZE0cLbD X-Google-Smtp-Source: APXvYqz5NCXreIdnYQdGhBkGQdho4Cjw9M7clGtOieGpTNyO+v/kCngHgT18s6Ee+84CHbD/K3d+HpY/brmlpOl2ap/3VTur9qP5 MIME-Version: 1.0 X-Received: by 2002:a02:a492:: with SMTP id d18mr6795099jam.27.1566341886589; Tue, 20 Aug 2019 15:58:06 -0700 (PDT) Date: Tue, 20 Aug 2019 15:58:06 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000bf410005909463ff@google.com> Subject: WARNING: refcount bug in cdev_get From: syzbot To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hello, syzbot found the following crash on: HEAD commit: 2d63ba3e Merge tag 'pm-5.3-rc5' of git://git.kernel.org/pu.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=165d3302600000 kernel config: https://syzkaller.appspot.com/x/.config?x=3ff364e429585cf2 dashboard link: https://syzkaller.appspot.com/bug?extid=82defefbbd8527e1c2cb compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16c8ab3c600000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16be0c4c600000 Bisection is inconclusive: the bug happens on the oldest tested release. bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11de3622600000 console output: https://syzkaller.appspot.com/x/log.txt?x=15de3622600000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+82defefbbd8527e1c2cb@syzkaller.appspotmail.com ------------[ cut here ]------------ refcount_t: increment on 0; use-after-free. WARNING: CPU: 1 PID: 11828 at lib/refcount.c:156 refcount_inc_checked lib/refcount.c:156 [inline] WARNING: CPU: 1 PID: 11828 at lib/refcount.c:156 refcount_inc_checked+0x61/0x70 lib/refcount.c:154 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 11828 Comm: syz-executor746 Not tainted 5.3.0-rc4+ #112 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+0x172/0x1f0 lib/dump_stack.c:113 panic+0x2dc/0x755 kernel/panic.c:219 __warn.cold+0x20/0x4c kernel/panic.c:576 report_bug+0x263/0x2b0 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:179 [inline] fixup_bug arch/x86/kernel/traps.c:174 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028 RIP: 0010:refcount_inc_checked lib/refcount.c:156 [inline] RIP: 0010:refcount_inc_checked+0x61/0x70 lib/refcount.c:154 Code: 1d 8e c6 64 06 31 ff 89 de e8 ab 9c 35 fe 84 db 75 dd e8 62 9b 35 fe 48 c7 c7 00 05 c6 87 c6 05 6e c6 64 06 01 e8 67 26 07 fe <0f> 0b eb c1 90 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41 RSP: 0018:ffff8880907d78b8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815c2466 RDI: ffffed10120faf09 RBP: ffff8880907d78c8 R08: ffff8880a771a200 R09: fffffbfff134ae48 R10: fffffbfff134ae47 R11: ffffffff89a5723f R12: ffff88809ea2bb80 R13: 0000000000000000 R14: ffff88809ff6cd40 R15: ffff8880a1c56480 kref_get include/linux/kref.h:45 [inline] kobject_get+0x66/0xc0 lib/kobject.c:644 cdev_get+0x60/0xb0 fs/char_dev.c:355 chrdev_open+0xb0/0x6b0 fs/char_dev.c:400 do_dentry_open+0x4df/0x1250 fs/open.c:797 vfs_open+0xa0/0xd0 fs/open.c:906 do_last fs/namei.c:3416 [inline] path_openat+0x10e9/0x4630 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1089 __do_sys_open fs/open.c:1107 [inline] __se_sys_open fs/open.c:1102 [inline] __x64_sys_open+0x7e/0xc0 fs/open.c:1102 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x406311 Code: 75 14 b8 02 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 18 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 02 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007f047e1c0960 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000406311 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f047e1c0970 RBP: 6666666666666667 R08: 000000000000000f R09: 00007f047e1c1700 R10: 00007f047e1c19d0 R11: 0000000000000293 R12: 00000000006dbc3c R13: 0000000000000000 R14: 0000000000000000 R15: 00000000317a7973 Kernel Offset: disabled Rebooting in 86400 seconds.. --- 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. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches