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=-0.4 required=3.0 tests=FROM_LOCAL_HEX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 F0F94ECDE46 for ; Thu, 25 Oct 2018 19:18:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A6D9A20834 for ; Thu, 25 Oct 2018 19:18:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A6D9A20834 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727707AbeJZDwJ (ORCPT ); Thu, 25 Oct 2018 23:52:09 -0400 Received: from mail-io1-f71.google.com ([209.85.166.71]:47878 "EHLO mail-io1-f71.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727230AbeJZDwI (ORCPT ); Thu, 25 Oct 2018 23:52:08 -0400 Received: by mail-io1-f71.google.com with SMTP id y8-v6so6787796ioc.14 for ; Thu, 25 Oct 2018 12:18:05 -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=LLVhVU3044hoAVTLDE4E1ZxGXIaEvaFj43UT2Qb2WvQ=; b=PzbNs3ArzKevrxQWP6MBR6ooDV7A914CP6K5qxSyyYXmaLQe7lJ8ouDjKOIgGVWj/m t3Ub+Su929Titje9IJRelw/bFh669eljUtRmUaTmjHSlwmPbfilFaZ8Q8/kbNI2TC3o2 dpmb/iz2I7biU5vKbA9D0w+mZZdC2LRiFZRAx7xnL1ROVI/6QAUbAoykyoCX8sKq1Rjb r1IAwdNNiHrrLklC3WUHecF2BsYFjkBUkiZKuAyxM/ZtoIVAV8ZppxAd64dxwq/majt4 yRPBz3dC9+b+oqux6IzIcveFSMFI51RVZgLbtKv3Ds5Fbcdp0c/e4CmrlpIPR9D9pjj4 S3vA== X-Gm-Message-State: AGRZ1gI3u6O1mgCAeehet8eom1w60NvaOGvquxbIDVPkKf/VSdCGTZsZ 0kSPRRNL3yIt4iMwiaUmpVj5oXqk4kd6saopaFwRFfchoVwj X-Google-Smtp-Source: AJdET5crzKQDtjrRQaH0b2aELohshPXKyD09gn4yUWvtax0DYgqOFY9PeYTHmNed45d0gaIrNsxrzyGpedIXAVPoWRGlfgL6CH/i MIME-Version: 1.0 X-Received: by 2002:a5e:d710:: with SMTP id v16-v6mr428727iom.26.1540495085135; Thu, 25 Oct 2018 12:18:05 -0700 (PDT) Date: Thu, 25 Oct 2018 12:18:05 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <00000000000053fea105791276d8@google.com> Subject: KASAN: use-after-free Read in drm_gem_object_release From: syzbot To: linux-kernel@vger.kernel.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 Hello, syzbot found the following crash on: HEAD commit: bd6bf7c10484 Merge tag 'pci-v4.20-changes' of git://git.ke.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1448a683400000 kernel config: https://syzkaller.appspot.com/x/.config?x=2dd8629d56664133 dashboard link: https://syzkaller.appspot.com/bug?extid=e73f2fb5ed5a5df36d33 compiler: gcc (GCC) 8.0.1 20180413 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11331de5400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1334e64d400000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92 drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98 drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751 drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847 ================================================================== BUG: KASAN: use-after-free in drm_gem_object_release+0xf1/0x110 drivers/gpu/drm/drm_gem.c:813 Read of size 8 at addr ffff8801d83d3410 by task syz-executor977/6742 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 __do_sys_ioctl fs/ioctl.c:709 [inline] __se_sys_ioctl fs/ioctl.c:707 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x445989 Code: e8 4c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 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 6b c8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffcf076f4e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffcf076f500 RCX: 0000000000445989 RDX: 0000000020000000 RSI: ffffffffffffffb2 RDI: 0000000000000003 RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000100 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000 CPU: 0 PID: 6742 Comm: syz-executor977 Not tainted 4.19.0+ #80 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 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 drm_gem_object_release+0xf1/0x110 drivers/gpu/drm/drm_gem.c:813 __vgem_gem_destroy drivers/gpu/drm/vgem/vgem_drv.c:175 [inline] vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:199 [inline] vgem_gem_dumb_create+0x1f8/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214 drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92 drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98 drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751 drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 __do_sys_ioctl fs/ioctl.c:709 [inline] __se_sys_ioctl fs/ioctl.c:707 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x445989 Code: e8 4c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 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 6b c8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffcf076f4e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffcf076f500 RCX: 0000000000445989 RDX: 0000000020000000 RSI: ffffffffffffffb2 RDI: 0000000000000003 RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000100 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000 Allocated by task 6742: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620 kmalloc include/linux/slab.h:513 [inline] kzalloc include/linux/slab.h:707 [inline] __vgem_gem_create+0x4c/0x100 drivers/gpu/drm/vgem/vgem_drv.c:158 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:187 [inline] vgem_gem_dumb_create+0xce/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214 drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92 drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98 drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751 drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 __do_sys_ioctl fs/ioctl.c:709 [inline] __se_sys_ioctl fs/ioctl.c:707 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 6742: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3813 vgem_gem_free_object+0xb6/0xe0 drivers/gpu/drm/vgem/vgem_drv.c:61 drm_gem_object_free+0xf1/0x2b0 drivers/gpu/drm/drm_gem.c:839 kref_put include/linux/kref.h:70 [inline] drm_gem_object_put_unlocked+0x14c/0x180 drivers/gpu/drm/drm_gem.c:895 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:192 [inline] vgem_gem_dumb_create+0x120/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214 drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92 drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98 drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751 drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 __do_sys_ioctl fs/ioctl.c:709 [inline] __se_sys_ioctl fs/ioctl.c:707 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 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 ffff8801d83d3300 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 272 bytes inside of 512-byte region [ffff8801d83d3300, ffff8801d83d3500) The buggy address belongs to the page: page:ffffea000760f4c0 count:1 mapcount:0 mapping:ffff8801da800940 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffffea0007473948 ffffea0007471dc8 ffff8801da800940 raw: 0000000000000000 ffff8801d83d3080 0000000100000006 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d83d3300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d83d3380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801d83d3400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801d83d3480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d83d3500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== ================================================================== CPU: 0 PID: 6778 Comm: syz-executor977 Tainted: G B 4.19.0+ #80 BUG: KASAN: double-free or invalid-free in __vgem_gem_destroy drivers/gpu/drm/vgem/vgem_drv.c:176 [inline] BUG: KASAN: double-free or invalid-free in vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:199 [inline] BUG: KASAN: double-free or invalid-free in vgem_gem_dumb_create+0x203/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214 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 fail_dump lib/fault-inject.c:51 [inline] should_fail.cold.4+0xa/0x17 lib/fault-inject.c:149 __should_failslab+0x124/0x180 mm/failslab.c:32 should_failslab+0x9/0x14 mm/slab_common.c:1557 slab_pre_alloc_hook mm/slab.h:423 [inline] slab_alloc mm/slab.c:3378 [inline] kmem_cache_alloc_trace+0x2d7/0x750 mm/slab.c:3618 kmalloc include/linux/slab.h:513 [inline] drm_vma_node_allow+0x5f/0x290 drivers/gpu/drm/drm_vma_manager.c:277 drm_gem_handle_create_tail+0x233/0x440 drivers/gpu/drm/drm_gem.c:409 drm_gem_handle_create+0x52/0x60 drivers/gpu/drm/drm_gem.c:452 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:191 [inline] vgem_gem_dumb_create+0x115/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214 drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92 drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98 drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751 drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 __do_sys_ioctl fs/ioctl.c:709 [inline] __se_sys_ioctl fs/ioctl.c:707 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x445989 Code: e8 4c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 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 6b c8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffcf076f4e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffcf076f500 RCX: 0000000000445989 RDX: 0000000020000000 RSI: ffffffffffffffb2 RDI: 0000000000000003 RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000100 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000 CPU: 1 PID: 6767 Comm: syz-executor977 Tainted: G B 4.19.0+ #80 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 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256 kasan_report_invalid_free+0x64/0xa0 mm/kasan/report.c:336 __kasan_slab_free+0x13a/0x150 mm/kasan/kasan.c:501 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3813 __vgem_gem_destroy drivers/gpu/drm/vgem/vgem_drv.c:176 [inline] vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:199 [inline] vgem_gem_dumb_create+0x203/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214 drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92 drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98 drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751 drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 __do_sys_ioctl fs/ioctl.c:709 [inline] __se_sys_ioctl fs/ioctl.c:707 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x445989 Code: e8 4c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 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 6b c8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffcf076f4e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffcf076f500 RCX: 0000000000445989 RDX: 0000000020000000 RSI: ffffffffffffffb2 RDI: 0000000000000003 RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000100 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000 Allocated by task 6767: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620 kmalloc include/linux/slab.h:513 [inline] kzalloc include/linux/slab.h:707 [inline] __vgem_gem_create+0x4c/0x100 drivers/gpu/drm/vgem/vgem_drv.c:158 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:187 [inline] vgem_gem_dumb_create+0xce/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214 drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92 drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98 drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751 drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 __do_sys_ioctl fs/ioctl.c:709 [inline] __se_sys_ioctl fs/ioctl.c:707 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 6767: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3813 vgem_gem_free_object+0xb6/0xe0 drivers/gpu/drm/vgem/vgem_drv.c:61 drm_gem_object_free+0xf1/0x2b0 drivers/gpu/drm/drm_gem.c:839 kref_put include/linux/kref.h:70 [inline] drm_gem_object_put_unlocked+0x14c/0x180 drivers/gpu/drm/drm_gem.c:895 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:192 [inline] vgem_gem_dumb_create+0x120/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214 drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92 drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98 drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751 drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 __do_sys_ioctl fs/ioctl.c:709 [inline] __se_sys_ioctl fs/ioctl.c:707 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 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 ffff8801d4974080 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 0 bytes inside of 512-byte region [ffff8801d4974080, ffff8801d4974280) The buggy address belongs to the page: page:ffffea0007525d00 count:1 mapcount:0 mapping:ffff8801da800940 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffffea0007558e48 ffffea00071d0508 ffff8801da800940 raw: 0000000000000000 ffff8801d4974080 0000000100000006 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d4973f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801d4974000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff8801d4974080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801d4974100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d4974180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ================================================================== --- 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