KASAN: use-after-free Read in drm_gem_object_release
Thomas Zimmermann
tzimmermann at suse.de
Tue Jul 14 08:46:16 UTC 2020
Am 14.07.20 um 09:41 schrieb Thomas Zimmermann:
> Hi
>
> Am 10.07.20 um 10:24 schrieb butt3rflyh4ck:
>> I report a bug (in linux-5.8.0-rc4) found by syzkaller.
>>
>> kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.8.0-rc4.config
>>
>> I test the reproducer and crash too.
>>
>> In the drm_em_vram_t() function, ttm_bo_init() function call
>> ttm_bo_init_reserved(),
>> the ttm_bo_init_reserved() function call ttm_bo_put(), it will free
>> gbo->bo that is struct ttm_buffer_object.
>>
>> then, goto the err_drm_gem_object_release lable,
>> drm_gem_object_release() function will free gbo->bo.base, so cause use
>> after free.
>
> Thanks for reporting. I think we recently had a patch for this problem,
> [1] but I asked for some changes. Are you in a position to test a fix?
>
> Best regards
> Thomas
>
>
> [1]
> https://lore.kernel.org/dri-devel/20200620062134.82961-1-jiayang5@huawei.com/
I sent out a patchset with this patch and a few additional changes.
https://lore.kernel.org/dri-devel/20200714083238.28479-1-tzimmermann@suse.de/T/#t
Best regards
Thomas
>
>>
>> crash log:
>> ==================================================================
>> BUG: KASAN: use-after-free in drm_gem_object_release+0xf7/0x120
>> drivers/gpu/drm/drm_gem.c:953
>> Read of size 8 at addr ffff888064dfd928 by task syz-executor.2/1320
>>
>> CPU: 1 PID: 1320 Comm: syz-executor.2 Not tainted 5.8.0-rc4+ #1
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>> 1.10.2-1ubuntu1 04/01/2014
>> Call Trace:
>> __dump_stack lib/dump_stack.c:77 [inline]
>> dump_stack+0x18f/0x20d lib/dump_stack.c:118
>> print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
>> __kasan_report mm/kasan/report.c:513 [inline]
>> kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
>> drm_gem_object_release+0xf7/0x120 drivers/gpu/drm/drm_gem.c:953
>> drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:211 [inline]
>> drm_gem_vram_create+0x3e6/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:244
>> drm_gem_vram_fill_create_dumb+0x17a/0x310
>> drivers/gpu/drm/drm_gem_vram_helper.c:615
>> drm_gem_vram_driver_dumb_create+0x51/0xb0
>> drivers/gpu/drm/drm_gem_vram_helper.c:710
>> drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
>> drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
>> drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
>> vfs_ioctl fs/ioctl.c:48 [inline]
>> ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
>> __do_sys_ioctl fs/ioctl.c:762 [inline]
>> __se_sys_ioctl fs/ioctl.c:760 [inline]
>> __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
>> do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> RIP: 0033:0x467a29
>> Code: Bad RIP value.
>> RSP: 002b:00007f98f2d40c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
>> RAX: ffffffffffffffda RBX: 000000000076bf00 RCX: 0000000000467a29
>> RDX: 0000000020000040 RSI: 00000000c02064b2 RDI: 0000000000000003
>> RBP: 000000000070c600 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f98f2d416bc
>> R13: 0000000000000297 R14: 0000000000702040 R15: 00000000004d2418
>>
>> Allocated by task 1320:
>> save_stack+0x1b/0x40 mm/kasan/common.c:48
>> set_track mm/kasan/common.c:56 [inline]
>> __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
>> kmem_cache_alloc_trace+0x14f/0x2d0 mm/slab.c:3551
>> kmalloc include/linux/slab.h:555 [inline]
>> kzalloc include/linux/slab.h:669 [inline]
>> drm_gem_vram_create+0x425/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:239
>> drm_gem_vram_fill_create_dumb+0x17a/0x310
>> drivers/gpu/drm/drm_gem_vram_helper.c:615
>> drm_gem_vram_driver_dumb_create+0x51/0xb0
>> drivers/gpu/drm/drm_gem_vram_helper.c:710
>> drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
>> drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
>> drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
>> vfs_ioctl fs/ioctl.c:48 [inline]
>> ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
>> __do_sys_ioctl fs/ioctl.c:762 [inline]
>> __se_sys_ioctl fs/ioctl.c:760 [inline]
>> __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
>> do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> Freed by task 1320:
>> save_stack+0x1b/0x40 mm/kasan/common.c:48
>> set_track mm/kasan/common.c:56 [inline]
>> kasan_set_free_info mm/kasan/common.c:316 [inline]
>> __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
>> __cache_free mm/slab.c:3426 [inline]
>> kfree+0x103/0x2c0 mm/slab.c:3757
>> ttm_bo_release+0xae1/0x1350 drivers/gpu/drm/ttm/ttm_bo.c:632
>> kref_put include/linux/kref.h:65 [inline]
>> ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:638 [inline]
>> ttm_bo_init_reserved+0xb04/0xd00 drivers/gpu/drm/ttm/ttm_bo.c:1339
>> ttm_bo_init+0x10e/0x330 drivers/gpu/drm/ttm/ttm_bo.c:1366
>> drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:202 [inline]
>> drm_gem_vram_create+0x3c1/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:244
>> drm_gem_vram_fill_create_dumb+0x17a/0x310
>> drivers/gpu/drm/drm_gem_vram_helper.c:615
>> drm_gem_vram_driver_dumb_create+0x51/0xb0
>> drivers/gpu/drm/drm_gem_vram_helper.c:710
>> drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
>> drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
>> drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
>> vfs_ioctl fs/ioctl.c:48 [inline]
>> ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
>> __do_sys_ioctl fs/ioctl.c:762 [inline]
>> __se_sys_ioctl fs/ioctl.c:760 [inline]
>> __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
>> do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> The buggy address belongs to the object at ffff888064dfd800
>> which belongs to the cache kmalloc-1k of size 1024
>> The buggy address is located 296 bytes inside of
>> 1024-byte region [ffff888064dfd800, ffff888064dfdc00)
>> The buggy address belongs to the page:
>> page:ffffea0001937f40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
>> flags: 0xfffe0000000200(slab)
>> raw: 00fffe0000000200 ffffea0000f3c248 ffffea0001ad7388 ffff88806bc00c40
>> raw: 0000000000000000 ffff888064dfd000 0000000100000002 0000000000000000
>> page dumped because: kasan: bad access detected
>>
>> Memory state around the buggy address:
>> ffff888064dfd800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ffff888064dfd880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>> ffff888064dfd900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ^
>> ffff888064dfd980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ffff888064dfda00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ==================================================================
>>
>> Regards,
>> butt3rflyh4ck.
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer
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