KASAN: use-after-free Read in vgem_gem_dumb_create

Status: fixed on 2020/04/15 17:19
Subsystems: dri
[Documentation on labels]
Reported-by: syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com
Fix commit: 4b848f20eda5 drm/vgem: Close use-after-free race in vgem_gem_create
First crash: 2378d, last: 2365d
Cause bisection: introduced by (bisect log) :
commit 7611750784664db46d0db95631e322aeb263dde7
Author: Alex Deucher <alexander.deucher@amd.com>
Date: Wed Jun 21 16:31:41 2017 +0000

  drm/amdgpu: use kernel is_power_of_2 rather than local version

Crash: BUG: sleeping function called from invalid context in tap_get_minor (log)
Repro: syz .config
  
▶ ▼ Discussions (7)
Title Replies (including bot) Last reply
[PATCH 4.14 00/78] 4.14.278-rc1 review 81 (81) 2022/05/11 11:03
[PATCH 4.19 00/88] 4.19.242-rc1 review 97 (97) 2022/05/11 10:08
[PATCH 5.5 00/80] 5.5.5-stable review 89 (89) 2020/02/19 18:52
[PATCH 5.4 00/66] 5.4.21-stable review 71 (71) 2020/02/19 18:09
[PATCH] drm/vgem: Close use-after-free race in vgem_gem_create 4 (4) 2020/02/06 18:05
KASAN: use-after-free Read in vgem_gem_dumb_create 4 (6) 2020/02/03 15:08
Re: KASAN: use-after-free Read in vgem_gem_dumb_create 5 (5) 2020/02/02 13:17
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 KASAN: use-after-free Read in vgem_gem_dumb_create 19 syz, C error 192 1432d 2377d 0/1 upstream: reported C repro on 2020/01/31 14:46
linux-4.19 KASAN: use-after-free Read in vgem_gem_dumb_create 19 syz, C 292 1247d 2377d 0/1 upstream: reported C repro on 2020/01/31 21:57

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in vgem_gem_dumb_create+0x238/0x250 drivers/gpu/drm/vgem/vgem_drv.c:221
Read of size 8 at addr ffff88809a2ee908 by task syz-executor815/10244

CPU: 1 PID: 10244 Comm: syz-executor815 Not tainted 5.5.0-syzkaller #0
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+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:641
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
 vgem_gem_dumb_create+0x238/0x250 drivers/gpu/drm/vgem/vgem_drv.c:221
 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100
 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786
 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x123/0x180 fs/ioctl.c:747
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x44c3e9
Code: e8 8c e7 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 1b cc fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f40263e9db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006ddc58 RCX: 000000000044c3e9
RDX: 0000000020000000 RSI: 00000000c02064b2 RDI: 0000000000000004
RBP: 00000000006ddc50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006ddc5c
R13: 00007ffed0d4362f R14: 00007f40263ea9c0 R15: 00000000006ddc5c

Allocated by task 10244:
 save_stack+0x23/0x90 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+0xcf/0xe0 mm/kasan/common.c:488
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529
 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3551
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:670 [inline]
 __vgem_gem_create+0x49/0x100 drivers/gpu/drm/vgem/vgem_drv.c:165
 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:194 [inline]
 vgem_gem_dumb_create+0xd7/0x250 drivers/gpu/drm/vgem/vgem_drv.c:217
 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100
 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786
 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x123/0x180 fs/ioctl.c:747
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 10244:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 vgem_gem_free_object+0xbe/0xe0 drivers/gpu/drm/vgem/vgem_drv.c:68
 drm_gem_object_free+0x100/0x220 drivers/gpu/drm/drm_gem.c:983
 kref_put include/linux/kref.h:65 [inline]
 drm_gem_object_put_unlocked drivers/gpu/drm/drm_gem.c:1017 [inline]
 drm_gem_object_put_unlocked+0x196/0x1c0 drivers/gpu/drm/drm_gem.c:1002
 vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:199 [inline]
 vgem_gem_dumb_create+0x115/0x250 drivers/gpu/drm/vgem/vgem_drv.c:217
 drm_mode_create_dumb+0x282/0x310 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_mode_create_dumb_ioctl+0x26/0x30 drivers/gpu/drm/drm_dumb_buffers.c:100
 drm_ioctl_kernel+0x244/0x300 drivers/gpu/drm/drm_ioctl.c:786
 drm_ioctl+0x54e/0xa60 drivers/gpu/drm/drm_ioctl.c:886
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x123/0x180 fs/ioctl.c:747
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809a2ee800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 264 bytes inside of
 1024-byte region [ffff88809a2ee800, ffff88809a2eec00)
The buggy address belongs to the page:
page:ffffea000268bb80 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002816448 ffffea0002551bc8 ffff8880aa400c40
raw: 0000000000000000 ffff88809a2ee000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809a2ee800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809a2ee880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809a2ee900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88809a2ee980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809a2eea00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/02/02 04:37 upstream 94f2630b1897 2274ad39 .config console log report syz C ci-upstream-kasan-gce-root
2020/02/12 10:19 upstream 359c92c02bfa a75b198c .config console log report syz ci-upstream-kasan-gce-root
2020/02/11 07:22 upstream 0a679e13ea30 084454ae .config console log report syz ci-upstream-kasan-gce-smack-root
2020/02/10 08:39 upstream d1ea35f4cdd4 35f5e45e .config console log report syz ci-upstream-kasan-gce-root
2020/02/08 21:24 upstream f757165705e9 06150bf1 .config console log report syz ci-upstream-kasan-gce-smack-root
2020/02/08 04:27 upstream 41dcd67e8868 06150bf1 .config console log report syz ci-upstream-kasan-gce-smack-root
2020/02/07 13:42 upstream 90568ecf5615 06150bf1 .config console log report syz ci-upstream-kasan-gce-root
2020/02/06 03:25 upstream 6992ca0dd017 662cf49a .config console log report syz ci-upstream-kasan-gce-smack-root
2020/02/04 00:12 upstream 754beeec1d90 93e5e335 .config console log report syz ci-upstream-kasan-gce-root
2020/02/03 06:43 upstream 46d6b7becb1d 93e5e335 .config console log report syz ci-upstream-kasan-gce-selinux-root
2020/02/02 11:36 upstream 94f2630b1897 2274ad39 .config console log report syz ci-upstream-kasan-gce-selinux-root
2020/02/01 00:35 upstream ccaaaf6fe5a5 c30117b2 .config console log report syz ci-upstream-kasan-gce-smack-root
2020/01/30 17:45 upstream 39bed42de2e7 5ed23f9a .config console log report syz ci-upstream-kasan-gce
2020/02/12 18:41 upstream 359c92c02bfa 84f4fc8a .config console log report ci-upstream-kasan-gce-smack-root
2020/01/30 17:13 upstream 39bed42de2e7 5ed23f9a .config console log report ci-upstream-kasan-gce
* Struck through repros no longer work on HEAD.