KASAN: use-after-free Read in reservation_object_test_signaled_rcu

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0c88e405 Linux 4.19.160
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1086fe43500000
kernel config: https://syzkaller.appspot.com/x/.config?x=baf69366a17513f7
dashboard link: https://syzkaller.appspot.com/bug?extid=e14062e58265cb7f7475
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11132243500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17947971500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e14062...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x2cb4/0x3ff0 kernel/locking/lockdep.c:3294
Read of size 8 at addr ffff8880a6320fd8 by task syz-executor912/10535

CPU: 1 PID: 10535 Comm: syz-executor912 Not tainted 4.19.160-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+0x1fc/0x2fe lib/dump_stack.c:118
print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
kasan_report_error.cold+0x8a/0x1c7 mm/kasan/report.c:354
kasan_report mm/kasan/report.c:412 [inline]
__asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
__lock_acquire+0x2cb4/0x3ff0 kernel/locking/lockdep.c:3294
lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3907
seqcount_lockdep_reader_access include/linux/seqlock.h:81 [inline]
read_seqcount_begin include/linux/seqlock.h:164 [inline]
reservation_object_test_signaled_rcu+0x194/0xdb0 drivers/dma-buf/reservation.c:600
vgem_fence_attach_ioctl+0x2c6/0x640 drivers/gpu/drm/vgem/vgem_fence.c:185
drm_ioctl_kernel+0x208/0x2a0 drivers/gpu/drm/drm_ioctl.c:757
drm_ioctl+0x507/0x9c0 drivers/gpu/drm/drm_ioctl.c:857
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
__do_sys_ioctl fs/ioctl.c:712 [inline]
__se_sys_ioctl fs/ioctl.c:710 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x44a6d9
Code: e8 0c 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 fb ca fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ff3c3e7cdb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 000000000044a6d9
RDX: 0000000020000140 RSI: 00000000c10c5541 RDI: 0000000000000005
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00007ffc07db75bf R14: 00007ff3c3e7d9c0 R15: 0000000000000000

Allocated by task 10535:
__do_kmalloc mm/slab.c:3727 [inline]
__kmalloc+0x15a/0x3c0 mm/slab.c:3736
kmalloc include/linux/slab.h:520 [inline]
kzalloc include/linux/slab.h:709 [inline]
dma_buf_export+0x1f1/0xa20 drivers/dma-buf/dma-buf.c:416
drm_gem_dmabuf_export+0x17/0x80 drivers/gpu/drm/drm_prime.c:365
drm_gem_prime_export+0x182/0x200 drivers/gpu/drm/drm_prime.c:546
attach_dmabuf drivers/gpu/drm/vgem/vgem_fence.c:124 [inline]
vgem_fence_attach_ioctl+0x395/0x640 drivers/gpu/drm/vgem/vgem_fence.c:173
drm_ioctl_kernel+0x208/0x2a0 drivers/gpu/drm/drm_ioctl.c:757
drm_ioctl+0x507/0x9c0 drivers/gpu/drm/drm_ioctl.c:857
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
__do_sys_ioctl fs/ioctl.c:712 [inline]
__se_sys_ioctl fs/ioctl.c:710 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 10544:
__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
dma_buf_release+0x329/0x630 drivers/dma-buf/dma-buf.c:80
__fput+0x2ce/0x890 fs/file_table.c:278
task_work_run+0x148/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x251/0x2a0 arch/x86/entry/common.c:167
prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a6320dc0
which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 536 bytes inside of
1024-byte region [ffff8880a6320dc0, ffff8880a63211c0)
The buggy address belongs to the page:
page:ffffea000298c800 count:1 mapcount:0 mapping:ffff88813bff0ac0 index:0x0 compound_mapcount: 0
flags: 0xfff00000008100(slab|head)
raw: 00fff00000008100 ffffea0002999188 ffffea0002999788 ffff88813bff0ac0
raw: 0000000000000000 ffff8880a6320040 0000000100000007 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880a6320e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a6320f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880a6320f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880a6321000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a6321080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[syzbot]

syzbot suspects this issue was fixed by commit:

commit 020a44cc54d65e673a13195e96fc0addbfd3a601
Author: Charles Baylis <cb-k...@fishzet.co.uk>
Date: Fri Jul 16 16:43:12 2021 +0000

drm: Return -ENOTTY for non-drm ioctls

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1637420e300000
start commit: 0c88e405c97e Linux 4.19.160
git tree: linux-4.19.y

kernel config: https://syzkaller.appspot.com/x/.config?x=baf69366a17513f7
dashboard link: https://syzkaller.appspot.com/bug?extid=e14062e58265cb7f7475

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11132243500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17947971500000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: drm: Return -ENOTTY for non-drm ioctls

For information about bisection process see: https://goo.gl/tpsmEJ#bisection