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From: Thomas Zimmermann <tzimmermann@suse.de>
To: butt3rflyh4ck <butterflyhuangxx@gmail.com>, security@kernel.org
Cc: robdclark@chromium.org, airlied@linux.ie,
	syzkaller-bugs@googlegroups.com, dri-devel@lists.freedesktop.org,
	chris@chris-wilson.co.uk, seanpaul@chromium.org,
	sam@ravnborg.org, emil.velikov@collabora.com
Subject: Re: KASAN: use-after-free Read in drm_gem_object_release
Date: Tue, 14 Jul 2020 09:41:00 +0200
Message-ID: <4f26b648-1595-3f9a-4236-3d1b3e7134a8@suse.de> (raw)
In-Reply-To: <CAFcO6XO58pV+j9gu5Hha3JUW555EPQo6ELTvxRyQ5PWu_1gsUA@mail.gmail.com>

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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/

> 
> 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@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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  parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-10  8:24 butt3rflyh4ck
2020-07-10 10:39 ` Greg KH
2020-07-10 11:52 ` Dan Carpenter
2020-07-10 14:01   ` butt3rflyh4ck
2020-07-10 14:03   ` butt3rflyh4ck
2020-07-13 16:12   ` Daniel Vetter
2020-07-13 16:47     ` butt3rflyh4ck
2020-07-14  7:41 ` Thomas Zimmermann [this message]
2020-07-14  8:46   ` Thomas Zimmermann
     [not found] <00000000000053fea105791276d8@google.com>
2018-10-29 11:51 ` Dmitry Vyukov

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