------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 23504 at lib/refcount.c:25 refcount_warn_saturate+0xff/0x1a0 lib/refcount.c:25
Modules linked in:
CPU: 1 PID: 23504 Comm: syz.7.5016 Not tainted 6.1.135-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:refcount_warn_saturate+0xff/0x1a0 lib/refcount.c:25
Code: 09 01 48 c7 c7 e0 cd be 8a e8 0d 57 45 fd 0f 0b eb e0 e8 24 46 79 fd c6 05 fe a2 e2 09 01 48 c7 c7 20 cd be 8a e8 f1 56 45 fd <0f> 0b eb c4 e8 08 46 79 fd c6 05 e3 a2 e2 09 01 48 c7 c7 80 cd be
RSP: 0018:ffffc90003377c88 EFLAGS: 00010046
RAX: b0eb776f87cc5700 RBX: 0000000000000002 RCX: 0000000000080000
RDX: ffffc900113b3000 RSI: 0000000000006fa7 RDI: 0000000000006fa8
RBP: ffffc90003377d70 R08: dffffc0000000000 R09: ffffed10171e4f34
R10: ffffed10171e4f34 R11: 1ffff110171e4f33 R12: dffffc0000000000
R13: ffffc90003377d00 R14: 0000000000000002 R15: ffff888055f22040
FS:  00007f4ea86226c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4ea8621f98 CR3: 00000000626d8000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 000000000000000e DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:-1 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 kref_get include/linux/kref.h:45 [inline]
 dma_fence_get include/linux/dma-fence.h:288 [inline]
 sync_timeline_signal+0x4a3/0x8a0 drivers/dma-buf/sw_sync.c:207
 sw_sync_ioctl_inc drivers/dma-buf/sw_sync.c:385 [inline]
 sw_sync_ioctl+0x43a/0xa60 drivers/dma-buf/sw_sync.c:400
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4ea778e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4ea8622038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4ea79b6240 RCX: 00007f4ea778e969
RDX: 0000200000000140 RSI: 0000000040045701 RDI: 000000000000000b
RBP: 00007f4ea7810ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f4ea79b6240 R15: 00007ffd3886ac88
 </TASK>