On Mon, Apr 6, 2020 at 8:46 AM syzbot syzbot+d3a7951ed361037407db@syzkaller.appspotmail.com wrote:

Hello,

syzbot found the following crash on:

HEAD commit: ffc1c20c Merge tag 'for-5.7/dm-changes' of git://git.kerne.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1690471fe00000 kernel config: https://syzkaller.appspot.com/x/.config?x=d6a1e2f9a9986236 dashboard link: https://syzkaller.appspot.com/bug?extid=d3a7951ed361037407db compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+d3a7951ed361037407db@syzkaller.appspotmail.com

+drivers/gpu/drm/virtio/virtgpu_object.c maintainers Now we have both mainline and linux-next boot broken (linux-next is broken for the past 40 days). No testing of new code happens.

NET: Registered protocol family 38 async_tx: api initialized (async) Key type asymmetric registered Asymmetric key parser 'x509' registered Asymmetric key parser 'pkcs8' registered Key type pkcs7_test registered Asymmetric key parser 'tpm_parser' registered Block layer SCSI generic (bsg) driver version 0.4 loaded (major 243) io scheduler mq-deadline registered io scheduler kyber registered io scheduler bfq registered hgafb: HGA card not detected. hgafb: probe of hgafb.0 failed with error -22 usbcore: registered new interface driver udlfb uvesafb: failed to execute /sbin/v86d uvesafb: make sure that the v86d helper is installed and executable uvesafb: Getting VBE info block failed (eax=0x4f00, err=-2) uvesafb: vbe_init() failed with -22 uvesafb: probe of uvesafb.0 failed with error -22 vga16fb: mapped to 0x00000000ab381a8e Console: switching to colour frame buffer device 80x30 fb0: VGA16 VGA frame buffer device input: Power Button as /devices/LNXSYSTM:00/LNXPWRBN:00/input/input0 ACPI: Power Button [PWRF] ioatdma: Intel(R) QuickData Technology Driver 5.00 PCI Interrupt Link [GSIF] enabled at IRQ 21 PCI Interrupt Link [GSIH] enabled at IRQ 23 N_HDLC line discipline registered with maxframe=4096 Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled 00:05: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A Cyclades driver 2.6 Initializing Nozomi driver 2.1d RocketPort device driver module, version 2.09, 12-June-2003 No rocketport ports found; unloading driver Non-volatile memory driver v1.3 Linux agpgart interface v0.103 [drm] Initialized vgem 1.0.0 20120112 for vgem on minor 0 [drm] Supports vblank timestamp caching Rev 2 (21.10.2013). [drm] Initialized vkms 1.0.0 20180514 for vkms on minor 1 usbcore: registered new interface driver udl [drm] pci: virtio-vga detected at 0000:00:01.0 fb0: switching to virtiodrmfb from VGA16 VGA Console: switching to colour VGA+ 80x25 virtio-pci 0000:00:01.0: vgaarb: deactivate vga console Console: switching to colour dummy device 80x25 [drm] features: -virgl +edid [drm] number of scanouts: 1 [drm] number of cap sets: 0 [drm] Initialized virtio_gpu 0.1.0 0 for virtio0 on minor 2 ================================================================== BUG: KASAN: slab-out-of-bounds in virtio_gpu_object_shmem_init drivers/gpu/drm/virtio/virtgpu_object.c:151 [inline] BUG: KASAN: slab-out-of-bounds in virtio_gpu_object_create+0x9f3/0xaa0 drivers/gpu/drm/virtio/virtgpu_object.c:230 Write of size 8 at addr ffff888027f7a388 by task swapper/0/1

CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.6.0-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:374 __kasan_report.cold+0x1a/0x32 mm/kasan/report.c:506 kasan_report+0xe/0x20 mm/kasan/common.c:641 virtio_gpu_object_shmem_init drivers/gpu/drm/virtio/virtgpu_object.c:151 [inline] virtio_gpu_object_create+0x9f3/0xaa0 drivers/gpu/drm/virtio/virtgpu_object.c:230 virtio_gpu_gem_create+0xaa/0x1d0 drivers/gpu/drm/virtio/virtgpu_gem.c:42 virtio_gpu_mode_dumb_create+0x21e/0x360 drivers/gpu/drm/virtio/virtgpu_gem.c:82 drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_client_buffer_create drivers/gpu/drm/drm_client.c:267 [inline] drm_client_framebuffer_create+0x1b7/0x770 drivers/gpu/drm/drm_client.c:412 drm_fb_helper_generic_probe+0x1e4/0x810 drivers/gpu/drm/drm_fb_helper.c:2039 drm_fb_helper_single_fb_probe drivers/gpu/drm/drm_fb_helper.c:1588 [inline] __drm_fb_helper_initial_config_and_unlock+0xb56/0x11e0 drivers/gpu/drm/drm_fb_helper.c:1746 drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:1841 [inline] drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:1833 [inline] drm_fbdev_client_hotplug+0x30f/0x580 drivers/gpu/drm/drm_fb_helper.c:2133 drm_fbdev_generic_setup drivers/gpu/drm/drm_fb_helper.c:2212 [inline] drm_fbdev_generic_setup+0x18b/0x295 drivers/gpu/drm/drm_fb_helper.c:2185 virtio_gpu_probe+0x28f/0x2de drivers/gpu/drm/virtio/virtgpu_drv.c:127 virtio_dev_probe+0x463/0x710 drivers/virtio/virtio.c:248 really_probe+0x281/0x6d0 drivers/base/dd.c:527 driver_probe_device+0x104/0x210 drivers/base/dd.c:701 device_driver_attach+0x108/0x140 drivers/base/dd.c:975 __driver_attach+0xda/0x240 drivers/base/dd.c:1052 bus_for_each_dev+0x14b/0x1d0 drivers/base/bus.c:305 bus_add_driver+0x4a2/0x5a0 drivers/base/bus.c:622 driver_register+0x1c4/0x330 drivers/base/driver.c:171 do_one_initcall+0x10a/0x7d0 init/main.c:1152 do_initcall_level init/main.c:1225 [inline] do_initcalls init/main.c:1241 [inline] do_basic_setup init/main.c:1261 [inline] kernel_init_freeable+0x501/0x5ae init/main.c:1445 kernel_init+0xd/0x1bb init/main.c:1352 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 1: save_stack+0x1b/0x80 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:515 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:488 kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] virtio_gpu_create_object+0x3c/0xe0 drivers/gpu/drm/virtio/virtgpu_object.c:128 drm_gem_shmem_create+0x83/0x330 drivers/gpu/drm/drm_gem_shmem_helper.c:58 virtio_gpu_object_create+0xa5/0xaa0 drivers/gpu/drm/virtio/virtgpu_object.c:199 virtio_gpu_gem_create+0xaa/0x1d0 drivers/gpu/drm/virtio/virtgpu_gem.c:42 virtio_gpu_mode_dumb_create+0x21e/0x360 drivers/gpu/drm/virtio/virtgpu_gem.c:82 drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94 drm_client_buffer_create drivers/gpu/drm/drm_client.c:267 [inline] drm_client_framebuffer_create+0x1b7/0x770 drivers/gpu/drm/drm_client.c:412 drm_fb_helper_generic_probe+0x1e4/0x810 drivers/gpu/drm/drm_fb_helper.c:2039 drm_fb_helper_single_fb_probe drivers/gpu/drm/drm_fb_helper.c:1588 [inline] __drm_fb_helper_initial_config_and_unlock+0xb56/0x11e0 drivers/gpu/drm/drm_fb_helper.c:1746 drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:1841 [inline] drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:1833 [inline] drm_fbdev_client_hotplug+0x30f/0x580 drivers/gpu/drm/drm_fb_helper.c:2133 drm_fbdev_generic_setup drivers/gpu/drm/drm_fb_helper.c:2212 [inline] drm_fbdev_generic_setup+0x18b/0x295 drivers/gpu/drm/drm_fb_helper.c:2185 virtio_gpu_probe+0x28f/0x2de drivers/gpu/drm/virtio/virtgpu_drv.c:127 virtio_dev_probe+0x463/0x710 drivers/virtio/virtio.c:248 really_probe+0x281/0x6d0 drivers/base/dd.c:527 driver_probe_device+0x104/0x210 drivers/base/dd.c:701 device_driver_attach+0x108/0x140 drivers/base/dd.c:975 __driver_attach+0xda/0x240 drivers/base/dd.c:1052 bus_for_each_dev+0x14b/0x1d0 drivers/base/bus.c:305 bus_add_driver+0x4a2/0x5a0 drivers/base/bus.c:622 driver_register+0x1c4/0x330 drivers/base/driver.c:171 do_one_initcall+0x10a/0x7d0 init/main.c:1152 do_initcall_level init/main.c:1225 [inline] do_initcalls init/main.c:1241 [inline] do_basic_setup init/main.c:1261 [inline] kernel_init_freeable+0x501/0x5ae init/main.c:1445 kernel_init+0xd/0x1bb init/main.c:1352 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 0: (stack is not available)

The buggy address belongs to the object at ffff888027f7a000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 904 bytes inside of 1024-byte region [ffff888027f7a000, ffff888027f7a400) The buggy address belongs to the page: page:ffffea00009fde80 refcount:1 mapcount:0 mapping:ffff88802c800c40 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea0000a49408 ffff88802c801850 ffff88802c800c40 raw: 0000000000000000 ffff888027f7a000 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected

Memory state around the buggy address: ffff888027f7a280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888027f7a300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

...

ffff888027f7a380: 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

                  ^

ffff888027f7a400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888027f7a480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================

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