KASAN: use-after-free Read in drm_gem_object_release

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syzbot

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Oct 25, 2018, 3:18:05 PM10/25/18
to linux-...@vger.kernel.org, syzkall...@googlegroups.com
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+e73f2f...@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.
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Dmitry Vyukov

unread,
Oct 29, 2018, 7:51:36 AM10/29/18
to syzbot, Gustavo Padovan, maarten....@linux.intel.com, se...@poorly.run, David Airlie, DRI, LKML, syzkall...@googlegroups.com
On Thu, Oct 25, 2018 at 9:18 PM, syzbot
<syzbot+e73f2f...@syzkaller.appspotmail.com> wrote:
> 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

+drm maintainers
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> For more options, visit https://groups.google.com/d/optout.

Eric Biggers

unread,
Feb 26, 2019, 3:49:37 PM2/26/19
to dri-...@lists.freedesktop.org, David Airlie, Daniel Vetter, Chris Wilson, syzkaller-bugs, linux-...@vger.kernel.org
From: Eric Biggers <ebig...@google.com>

If drm_gem_handle_create() fails in vgem_gem_create(), then the
drm_vgem_gem_object is freed twice: once when the reference is dropped
by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy().

This was hit by syzkaller using fault injection.

Fix it by skipping the second free.

Reported-by: syzbot+e73f2f...@syzkaller.appspotmail.com
Fixes: 5ba6c9ff961a ("drm/vgem: Fix mmaping")
Cc: sta...@vger.kernel.org
Signed-off-by: Eric Biggers <ebig...@google.com>
---
drivers/gpu/drm/vgem/vgem_drv.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 5930facd6d2d8..70646d9da1596 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -189,15 +189,13 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
return ERR_CAST(obj);

ret = drm_gem_handle_create(file, &obj->base, handle);
+
drm_gem_object_put_unlocked(&obj->base);
+
if (ret)
- goto err;
+ return ERR_PTR(ret);

return &obj->base;
-
-err:
- __vgem_gem_destroy(obj);
- return ERR_PTR(ret);
}

static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
--
2.21.0.rc2.261.ga7da99ff1b-goog

Chris Wilson

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Feb 26, 2019, 4:01:43 PM2/26/19
to Daniel Vetter, David Airlie, Eric Biggers, dri-...@lists.freedesktop.org, syzkaller-bugs, linux-...@vger.kernel.org
Quoting Eric Biggers (2019-02-26 20:47:26)
> From: Eric Biggers <ebig...@google.com>
>
> If drm_gem_handle_create() fails in vgem_gem_create(), then the
> drm_vgem_gem_object is freed twice: once when the reference is dropped
> by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy().
>
> This was hit by syzkaller using fault injection.
>
> Fix it by skipping the second free.
>
> Reported-by: syzbot+e73f2f...@syzkaller.appspotmail.com
> Fixes: 5ba6c9ff961a ("drm/vgem: Fix mmaping")

That's the wrong fixes line, it's
Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces")
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Laura Abbott <lab...@redhat.com>
Cc: Daniel Vetter <daniel...@ffwll.ch>

Sadly I reviewed it so I'm still culpable, but the fix is correct as the
put purposely frees it on error.

> Cc: sta...@vger.kernel.org
> Signed-off-by: Eric Biggers <ebig...@google.com>

> ---
> drivers/gpu/drm/vgem/vgem_drv.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index 5930facd6d2d8..70646d9da1596 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -189,15 +189,13 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
> return ERR_CAST(obj);
>
> ret = drm_gem_handle_create(file, &obj->base, handle);
> +
> drm_gem_object_put_unlocked(&obj->base);
> +

The pattern in the other GEM drivers is not to have these extra
newlines.

Reviewed-by: Chris Wilson <ch...@chris-wilson.co.uk>

Eric Biggers

unread,
Feb 26, 2019, 4:30:56 PM2/26/19
to Chris Wilson, Daniel Vetter, David Airlie, dri-...@lists.freedesktop.org, syzkaller-bugs, linux-...@vger.kernel.org
On Tue, Feb 26, 2019 at 09:01:29PM +0000, Chris Wilson wrote:
> Quoting Eric Biggers (2019-02-26 20:47:26)
> > From: Eric Biggers <ebig...@google.com>
> >
> > If drm_gem_handle_create() fails in vgem_gem_create(), then the
> > drm_vgem_gem_object is freed twice: once when the reference is dropped
> > by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy().
> >
> > This was hit by syzkaller using fault injection.
> >
> > Fix it by skipping the second free.
> >
> > Reported-by: syzbot+e73f2f...@syzkaller.appspotmail.com
> > Fixes: 5ba6c9ff961a ("drm/vgem: Fix mmaping")
>
> That's the wrong fixes line, it's
> Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces")
> Cc: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: Laura Abbott <lab...@redhat.com>
> Cc: Daniel Vetter <daniel...@ffwll.ch>
>
> Sadly I reviewed it so I'm still culpable, but the fix is correct as the
> put purposely frees it on error.
>

You're right; I misread the code at that commit.
I'll resend with the correct tags.

Eric Biggers

unread,
Feb 26, 2019, 4:45:36 PM2/26/19
to dri-...@lists.freedesktop.org, Chris Wilson, syzkaller-bugs, linux-...@vger.kernel.org, syzbot+e73f2f...@syzkaller.appspotmail.com, Laura Abbott, Daniel Vetter, sta...@vger.kernel.org
From: Eric Biggers <ebig...@google.com>

If drm_gem_handle_create() fails in vgem_gem_create(), then the
drm_vgem_gem_object is freed twice: once when the reference is dropped
by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy().

This was hit by syzkaller using fault injection.

Fix it by skipping the second free.

Reported-by: syzbot+e73f2f...@syzkaller.appspotmail.com
Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces")
Reviewed-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Laura Abbott <lab...@redhat.com>
Cc: Daniel Vetter <daniel...@ffwll.ch>
Cc: sta...@vger.kernel.org
Signed-off-by: Eric Biggers <ebig...@google.com>
---
drivers/gpu/drm/vgem/vgem_drv.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 5930facd6d2d8..11a8f99ba18c5 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -191,13 +191,9 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
ret = drm_gem_handle_create(file, &obj->base, handle);
drm_gem_object_put_unlocked(&obj->base);

Eric Biggers

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Feb 26, 2019, 5:09:30 PM2/26/19
to dri-...@lists.freedesktop.org, syzkaller-bugs, linux-...@vger.kernel.org, Rodrigo Siqueira, Haneen Mohammed, Daniel Vetter, Chris Wilson, sta...@vger.kernel.org
From: Eric Biggers <ebig...@google.com>

If drm_gem_handle_create() fails in vkms_gem_create(), then the
vkms_gem_object is freed twice: once when the reference is dropped by
drm_gem_object_put_unlocked(), and again by the extra calls to
drm_gem_object_release() and kfree().

Fix it by skipping the second release and free.

This bug was originally found in the vgem driver by syzkaller using
fault injection, but I noticed it's also present in the vkms driver.

Fixes: 559e50fd34d1 ("drm/vkms: Add dumb operations")
Cc: Rodrigo Siqueira <rodrigosi...@gmail.com>
Cc: Haneen Mohammed <hamoha...@gmail.com>
Cc: Daniel Vetter <daniel...@ffwll.ch>
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: sta...@vger.kernel.org
Signed-off-by: Eric Biggers <ebig...@google.com>
---
drivers/gpu/drm/vkms/vkms_gem.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_gem.c b/drivers/gpu/drm/vkms/vkms_gem.c
index 138b0bb325cf9..69048e73377dc 100644
--- a/drivers/gpu/drm/vkms/vkms_gem.c
+++ b/drivers/gpu/drm/vkms/vkms_gem.c
@@ -111,11 +111,8 @@ struct drm_gem_object *vkms_gem_create(struct drm_device *dev,

ret = drm_gem_handle_create(file, &obj->gem, handle);
drm_gem_object_put_unlocked(&obj->gem);
- if (ret) {
- drm_gem_object_release(&obj->gem);
- kfree(obj);
+ if (ret)
return ERR_PTR(ret);
- }

return &obj->gem;
}
--
2.21.0.rc2.261.ga7da99ff1b-goog

Chris Wilson

unread,
Feb 26, 2019, 5:15:08 PM2/26/19
to Eric Biggers, dri-...@lists.freedesktop.org, syzkaller-bugs, linux-...@vger.kernel.org, Rodrigo Siqueira, Haneen Mohammed, Daniel Vetter, sta...@vger.kernel.org
Quoting Eric Biggers (2019-02-26 22:08:58)
> From: Eric Biggers <ebig...@google.com>
>
> If drm_gem_handle_create() fails in vkms_gem_create(), then the
> vkms_gem_object is freed twice: once when the reference is dropped by
> drm_gem_object_put_unlocked(), and again by the extra calls to
> drm_gem_object_release() and kfree().
>
> Fix it by skipping the second release and free.
>
> This bug was originally found in the vgem driver by syzkaller using
> fault injection, but I noticed it's also present in the vkms driver.
>
> Fixes: 559e50fd34d1 ("drm/vkms: Add dumb operations")
> Cc: Rodrigo Siqueira <rodrigosi...@gmail.com>
> Cc: Haneen Mohammed <hamoha...@gmail.com>
> Cc: Daniel Vetter <daniel...@ffwll.ch>
> Cc: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: sta...@vger.kernel.org
> Signed-off-by: Eric Biggers <ebig...@google.com>
Reviewed-by: Chris Wilson <ch...@chris-wilson.co.uk>
-Chris

Rodrigo Siqueira

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Feb 27, 2019, 6:12:07 PM2/27/19
to Eric Biggers, dri-...@lists.freedesktop.org, syzkaller-bugs, linux-...@vger.kernel.org, Haneen Mohammed, Daniel Vetter, Chris Wilson, sta...@vger.kernel.org
Hi,

Thanks for your patch! :)

The patch looks good for me. I also tested it under the IGT tests on my
local VM and everything was fine.

Reviewed-by: Rodrigo Siqueira <rodrigosi...@gmail.com>

--
Rodrigo Siqueira
https://siqueira.tech
Graduate Student
Department of Computer Science
University of São Paulo
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Laura Abbott

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Feb 27, 2019, 6:52:50 PM2/27/19
to Eric Biggers, dri-...@lists.freedesktop.org, Chris Wilson, syzkaller-bugs, linux-...@vger.kernel.org, syzbot+e73f2f...@syzkaller.appspotmail.com, Daniel Vetter, sta...@vger.kernel.org
Acked-by: Laura Abbott <lab...@redhat.com>

Dmitry Vyukov

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Feb 28, 2019, 1:41:56 AM2/28/19
to Rodrigo Siqueira, Eric Biggers, DRI, syzkaller-bugs, LKML, Haneen Mohammed, Daniel Vetter, Chris Wilson, stable
Hi Rodrigo,

What are IGT tests? How can I run them?

>
> Reviewed-by: Rodrigo Siqueira <rodrigosi...@gmail.com>
>
> --
> Rodrigo Siqueira
> https://siqueira.tech
> Graduate Student
> Department of Computer Science
> University of São Paulo
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bug...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20190227231202.tycdbcqtk5ylwp4k%40smtp.gmail.com.

Rodrigo Siqueira

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Mar 4, 2019, 6:23:18 PM3/4/19
to Dmitry Vyukov, Eric Biggers, DRI, syzkaller-bugs, LKML, Haneen Mohammed, Daniel Vetter, Chris Wilson, stable
Hi,

Patch applied to drm-misc-fixes.

> Hi Rodrigo,
>
> What are IGT tests? How can I run them?

Hi Dmitry,

IGT is a test suite focused on DRM drivers.

You can clone the project using the link below:

https://gitlab.freedesktop.org/drm/igt-gpu-tools.git

In the README, you will find the software dependencies. After you
install all the required package, just use:

mkdir build && meson build && cd build && ninja

Finally, if you want to test VKMS, I recommend you to do it inside a VM.

Best Regards
Rodrigo Siqueira
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Rodrigo Siqueira

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Mar 4, 2019, 6:24:45 PM3/4/19
to Eric Biggers, dri-...@lists.freedesktop.org, Daniel Vetter, syzkaller-bugs, linux-...@vger.kernel.org, sta...@vger.kernel.org, syzbot+e73f2f...@syzkaller.appspotmail.com
On 02/26, Eric Biggers wrote:
> _______________________________________________
> dri-devel mailing list
> dri-...@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

Applied to drm-misc-fixes.

Thanks
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Dmitry Vyukov

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Mar 5, 2019, 9:26:10 AM3/5/19
to Rodrigo Siqueira, Eric Biggers, DRI, syzkaller-bugs, LKML, Haneen Mohammed, Daniel Vetter, Chris Wilson, stable
On Tue, Mar 5, 2019 at 12:23 AM Rodrigo Siqueira
Hi Rodrigo,

Thanks for the info, but this did not work for me.
I installed all recommended packages (including libdw-dev), but then got:

igt-gpu-tools$ mkdir -p build && meson build && cd build && ninja
The Meson build system
Version: 0.46.1
Source dir: /src/igt-gpu-tools
Build dir: /src/igt-gpu-tools/build
Build type: native build
Project name: igt-gpu-tools
Native C compiler: ccache cc (gcc 7.3.0 "cc (Debian 7.3.0-5) 7.3.0")
Build machine cpu family: x86_64
Build machine cpu: x86_64
Compiler for C supports arguments -Wbad-function-cast: YES
Compiler for C supports arguments -Wdeclaration-after-statement: YES
Compiler for C supports arguments -Wformat=2: YES
Compiler for C supports arguments -Wimplicit-fallthrough=0: YES
Compiler for C supports arguments -Wlogical-op: YES
Compiler for C supports arguments -Wmissing-declarations: YES
Compiler for C supports arguments -Wmissing-format-attribute: YES
Compiler for C supports arguments -Wmissing-noreturn: YES
Compiler for C supports arguments -Wmissing-prototypes: YES
Compiler for C supports arguments -Wnested-externs: YES
Compiler for C supports arguments -Wold-style-definition: YES
Compiler for C supports arguments -Wpointer-arith: YES
Compiler for C supports arguments -Wredundant-decls: YES
Compiler for C supports arguments -Wshadow: YES
Compiler for C supports arguments -Wstrict-prototypes: YES
Compiler for C supports arguments -Wuninitialized: YES
Compiler for C supports arguments -Wunused: YES
Compiler for C supports arguments -Wno-clobbered -Wclobbered: YES
Compiler for C supports arguments -Wno-maybe-uninitialized
-Wmaybe-uninitialized: YES
Compiler for C supports arguments -Wno-missing-field-initializers
-Wmissing-field-initializers: YES
Compiler for C supports arguments -Wno-pointer-arith -Wpointer-arith: YES
Compiler for C supports arguments -Wno-sign-compare -Wsign-compare: YES
Compiler for C supports arguments -Wno-type-limits -Wtype-limits: YES
Compiler for C supports arguments -Wno-unused-parameter -Wunused-parameter: YES
Compiler for C supports arguments -Wno-unused-result -Wunused-result: YES
Compiler for C supports arguments -Werror=address: YES
Compiler for C supports arguments -Werror=array-bounds: YES
Compiler for C supports arguments -Werror=implicit: YES
Compiler for C supports arguments -Werror=init-self: YES
Compiler for C supports arguments -Werror=int-to-pointer-cast: YES
Compiler for C supports arguments -Werror=main: YES
Compiler for C supports arguments -Werror=missing-braces: YES
Compiler for C supports arguments -Werror=nonnull: YES
Compiler for C supports arguments -Werror=pointer-to-int-cast: YES
Compiler for C supports arguments -Werror=return-type: YES
Compiler for C supports arguments -Werror=sequence-point: YES
Compiler for C supports arguments -Werror=trigraphs: YES
Compiler for C supports arguments -Werror=write-strings: YES
Found pkg-config: /usr/bin/pkg-config (0.29)
Native dependency libdrm found: YES 2.4.91
Native dependency libdrm_intel found: YES 2.4.91
Native dependency libdrm_nouveau found: YES 2.4.91
Native dependency libdrm_amdgpu found: YES 2.4.91
Native dependency pciaccess found: YES 0.13.4
Native dependency libkmod found: YES 24
Native dependency libprocps found: YES 3.3.15
Native dependency libunwind found: YES 1.21

meson.build:151:0: ERROR: Could not generate cargs for libdw:

A full log can be found at /src/igt-gpu-tools/build/meson-logs/meson-log.txt


and meson-log.txt ends with:

Compiler for C supports arguments -Werror=write-strings: YES
Found pkg-config: /usr/bin/pkg-config (0.29)
Determining dependency 'libdrm' with pkg-config executable '/usr/bin/pkg-config'
Native dependency libdrm found: YES 2.4.91
Determining dependency 'libdrm_intel' with pkg-config executable
'/usr/bin/pkg-config'
Native dependency libdrm_intel found: YES 2.4.91
Determining dependency 'libdrm_nouveau' with pkg-config executable
'/usr/bin/pkg-config'
Native dependency libdrm_nouveau found: YES 2.4.91
Determining dependency 'libdrm_amdgpu' with pkg-config executable
'/usr/bin/pkg-config'
Native dependency libdrm_amdgpu found: YES 2.4.91
Determining dependency 'pciaccess' with pkg-config executable
'/usr/bin/pkg-config'
Native dependency pciaccess found: YES 0.13.4
Determining dependency 'libkmod' with pkg-config executable
'/usr/bin/pkg-config'
Native dependency libkmod found: YES 24
Determining dependency 'libprocps' with pkg-config executable
'/usr/bin/pkg-config'
Native dependency libprocps found: YES 3.3.15
Determining dependency 'libunwind' with pkg-config executable
'/usr/bin/pkg-config'
Native dependency libunwind found: YES 1.21
Determining dependency 'libdw' with pkg-config executable '/usr/bin/pkg-config'

meson.build:151:0: ERROR: Could not generate cargs for libdw:

Rodrigo Siqueira

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Mar 10, 2019, 11:36:25 AM3/10/19
to Dmitry Vyukov, Eric Biggers, DRI, syzkaller-bugs, LKML, Haneen Mohammed, Daniel Vetter, Chris Wilson, stable
Hi Dmitry,

I would like to recommend you to join the dri-devel channel (Freenode).
There you can quickly get help from me and others ;)

My nick in the dri-devel is 'siqueira'.

Best Regards
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