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[BUG] pyservicemaker: Buffer.extract() returns a null tensor that segfaults on use for non-RGB surfaces or an out-of-range batch_id

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Bewertung

Schwierigkeit
3/5
Geschätzter Aufwand
1-2 Tage
Anfängerfreundlichkeit
72/100
Issue-Typ
Bug
Klarheit
Klar beschrieben
Aktivitätsstatus
Aktiv
Tech-Stack
cpp, python
Bereich
backend, computer-vision

Rechercherichtung

Start with Buffer::extract() in src/service-maker/sources/core/src/buffer.cpp and the Python binding in src/service-maker/sources/python/src/bindings/buffer.h. Trace how an unsupported surface format and an out-of-range batch_id reach the returned tensor, then run the provided repro.py with RGBA, NV12, and RGB. Done means invalid inputs fail safely and the reported reproductions no longer segfault; RGBA support is described as an additional possibility, not a required fix.

Vom Indexierungsmodell aus dem Issue-Text verfasst.

Beschreibung

Describe the bug

Buffer.extract(batch_id) returns a Tensor object even when it cannot extract anything. Using that object (here reading tensor.shape) segfaults the process. This happens in two cases:

  1. The surface is not RGB, for example RGBA or NV12. RGBA is the format nvdsosd and nvmultistreamtiler work in, so this is the format an application is most likely to have.
  2. batch_id is not below the number of frames in the batch.

In both cases the only hint is a g_printerr line, "Only RGB format is supported for being extracted as a tensor", which is also misleading in the second case.

Buffer::extract() leaves tensor as nullptr for every surface that is not RGB and returns it after the g_printerr. It reads surface_batch->surfaceList[batchId] without checking batchId against numFilled, so an out-of-range id reads past the end of the list (here the read colour format is not RGB, so it ends in the same nullptr). The Python binding wraps the result in TensorWrapper without checking for nullptr.

Steps/Code to reproduce bug

Save as repro.py:

import faulthandler
import sys

from pyservicemaker import BufferOperator, Pipeline, Probe

faulthandler.enable()


class Extract(BufferOperator):
    def __init__(self):
        super().__init__()
        self.done = False

    def handle_buffer(self, buffer):
        if not self.done:
            self.done = True
            tensor = buffer.extract(0)
            print(f"extract(0) returned {type(tensor).__name__}", flush=True)
            print(f"shape {tensor.shape}", flush=True)
        return True


pipeline = Pipeline("extract")
pipeline.add("videotestsrc", "src", {"num-buffers": 30})
pipeline.add("nvvideoconvert", "conv", {})
pipeline.add("capsfilter", "caps", {"caps": f"video/x-raw(memory:NVMM), format={sys.argv[1]}"})
pipeline.add("fakesink", "sink", {"sync": False})
pipeline.link("src", "conv", "caps", "sink")
pipeline.attach("caps", Probe("extract", Extract()))
pipeline.start()
pipeline.wait()
print("wait() returned")

Run it in the stock container (pyyaml is installed first because import pyservicemaker needs it, see #98):

docker run --rm --gpus all -v "$PWD":/repro --entrypoint bash nvcr.io/nvidia/deepstream:9.1-triton-multiarch \
  -c "pip install -q --break-system-packages pyyaml && python3 /repro/repro.py RGBA; echo exit code \$?"

RGB works:

extract(0) returned Tensor
shape (240, 320, 3)
...
wait() returned
exit code 0

RGBA and NV12 segfault on tensor.shape:

Only RGB format is supported for being extracted as a tensor
extract(0) returned Tensor
Fatal Python error: Segmentation fault

Current thread 0x00007798613fd6c0 (most recent call first):
  File "/repro/repro.py", line 19 in handle_buffer
...
exit code 139

With RGB and buffer.extract(1) in place of buffer.extract(0) (a batch of one frame), the output is the same: the "Only RGB format" line, then a segfault, exit code 139.

Expected behavior

  1. extract() raises a Python exception (for example ValueError) when the surface format is not supported or batch_id is out of range, or returns None. It never returns an object that crashes on use.
  2. extract() checks batch_id against numFilled.
  3. If possible, extract() also supports RGBA (shape (height, width, 4), strides (pitch, 4, 1)). Today an application that needs pixels after nvdsosd or the tiler has to add an nvvideoconvert to RGB only for this.

Environment details

  • Environment location: Docker on bare-metal (Ubuntu 26.04.1 LTS host, RTX A4000 Laptop GPU, driver 595.99.02)
  • Method of DeepStream install: Docker, nvcr.io/nvidia/deepstream:9.1-triton-multiarch (digest sha256:fd31f5b44ababdbdee8cd397a375e888191b49e402ac237254a4cdc239130f5b), DeepStream 9.1.0, pyservicemaker 0.0.1, TensorRT 10.16.0.72, CUDA 13.2
  • Docker command: see the steps above
  • scripts/print_env.sh output, run inside the same container:
Click here to see environment details
 **git***
 Not inside a git repository
 
 ***OS Information***
 DISTRIB_ID=Ubuntu
 DISTRIB_RELEASE=24.04
 DISTRIB_CODENAME=noble
 DISTRIB_DESCRIPTION="Ubuntu 24.04.4 LTS"
 PRETTY_NAME="Ubuntu 24.04.4 LTS"
 NAME="Ubuntu"
 VERSION_ID="24.04"
 VERSION="24.04.4 LTS (Noble Numbat)"
 VERSION_CODENAME=noble
 ID=ubuntu
 ID_LIKE=debian
 HOME_URL="https://www.ubuntu.com/"
 SUPPORT_URL="https://help.ubuntu.com/"
 BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
 PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
 UBUNTU_CODENAME=noble
 LOGO=ubuntu-logo
 Linux b5ade298bb5a 7.0.0-38-generic #38-Ubuntu SMP PREEMPT_DYNAMIC Fri Sep  4 09:10:14 UTC 2026 x86_64 x86_64 x86_64 GNU/Linux
 
 ***GPU Information***
 Thu Oct 22 14:52:51 2026
 +-----------------------------------------------------------------------------------------+
 | NVIDIA-SMI 595.99.02              Driver Version: 595.99.02      CUDA Version: 13.2     |
 +-----------------------------------------+------------------------+----------------------+
 | GPU  Name                 Persistence-M | Bus-Id          Disp.A | Volatile Uncorr. ECC |
 | Fan  Temp   Perf          Pwr:Usage/Cap |           Memory-Usage | GPU-Util  Compute M. |
 |                                         |                        |               MIG M. |
 |=========================================+========================+======================|
 |   0  NVIDIA RTX A4000 Laptop GPU    Off |   00000000:01:00.0 Off |                  N/A |
 | N/A   63C    P0             25W /   80W |     161MiB /   8192MiB |      0%      Default |
 |                                         |                        |                  N/A |
 +-----------------------------------------+------------------------+----------------------+
 
 +-----------------------------------------------------------------------------------------+
 | Processes:                                                                              |
 |  GPU   GI   CI              PID   Type   Process name                        GPU Memory |
 |        ID   ID                                                               Usage      |
 |=========================================================================================|
 |  No running processes found                                                             |
 +-----------------------------------------------------------------------------------------+
 
 ***CPU***
 Architecture:                            x86_64
 CPU op-mode(s):                          32-bit, 64-bit
 Address sizes:                           39 bits physical, 48 bits virtual
 Byte Order:                              Little Endian
 CPU(s):                                  16
 On-line CPU(s) list:                     0-15
 Vendor ID:                               GenuineIntel
 Model name:                              11th Gen Intel(R) Core(TM) i9-11950H @ 2.60GHz
 CPU family:                              6
 Model:                                   141
 Thread(s) per core:                      2
 Core(s) per socket:                      8
 Socket(s):                               1
 Stepping:                                1
 CPU(s) scaling MHz:                      42%
 CPU max MHz:                             5000.0000
 CPU min MHz:                             800.0000
 BogoMIPS:                                5222.40
 Flags:                                   fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l2 cdp_l2 ssbd ibrs ibpb stibp ibrs_enhanced tpr_shadow flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid rdt_a avx512f avx512dq rdseed adx smap avx512ifma clflushopt clwb intel_pt avx512cd sha_ni avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves split_lock_detect user_shstk dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_epp hwp_pkg_req vnmi avx512vbmi umip pku ospke avx512_vbmi2 gfni vaes vpclmulqdq avx512_vnni avx512_bitalg avx512_vpopcntdq rdpid movdiri movdir64b fsrm avx512_vp2intersect md_clear ibt flush_l1d arch_capabilities
 Virtualization:                          VT-x
 L1d cache:                               384 KiB (8 instances)
 L1i cache:                               256 KiB (8 instances)
 L2 cache:                                10 MiB (8 instances)
 L3 cache:                                24 MiB (1 instance)
 NUMA node(s):                            1
 NUMA node0 CPU(s):                       0-15
 Vulnerability Gather data sampling:      Vulnerable
 Vulnerability Ghostwrite:                Not affected
 Vulnerability Indirect target selection: Mitigation; Aligned branch/return thunks
 Vulnerability Itlb multihit:             Not affected
 Vulnerability L1tf:                      Not affected
 Vulnerability Mds:                       Not affected
 Vulnerability Meltdown:                  Not affected
 Vulnerability Mmio stale data:           Not affected
 Vulnerability Old microcode:             Not affected
 Vulnerability Reg file data sampling:    Not affected
 Vulnerability Retbleed:                  Not affected
 Vulnerability Spec rstack overflow:      Not affected
 Vulnerability Spec store bypass:         Mitigation; Speculative Store Bypass disabled via prctl
 Vulnerability Spectre v1:                Mitigation; usercopy/swapgs barriers and __user pointer sanitization
 Vulnerability Spectre v2:                Mitigation; Enhanced / Automatic IBRS; IBPB conditional; PBRSB-eIBRS SW sequence; BHI SW loop, KVM SW loop
 Vulnerability Srbds:                     Not affected
 Vulnerability Tsa:                       Not affected
 Vulnerability Tsx async abort:           Not affected
 Vulnerability Vmscape:                   Not affected
 
 ***CMake***
 /usr/bin/cmake
 cmake version 3.28.3
 
 CMake suite maintained and supported by Kitware (kitware.com/cmake).
 
 ***g++***
 /usr/bin/g++
 g++ (Ubuntu 13.3.0-6ubuntu2~24.04.1) 13.3.0
 Copyright (C) 2023 Free Software Foundation, Inc.
 This is free software; see the source for copying conditions.  There is NO
 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 
 
 ***nvcc***
 /usr/local/cuda/bin/nvcc
 nvcc: NVIDIA (R) Cuda compiler driver
 Copyright (c) 2005-2026 NVIDIA Corporation
 Built on Mon_Mar_02_09:52:23_PM_PST_2026
 Cuda compilation tools, release 13.2, V13.2.51
 Build cuda_13.2.r13.2/compiler.37434383_0
 
 ***Python***
 
 ***Environment Variables***
 PATH                            : /opt/proto/bin:/opt/tritonserver/bin:/usr/local/nvidia/bin:/usr/local/cuda/bin:/usr/local/mpi/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/ucx/bin:/opt/amazon/efa/bin:/.local/bin
 LD_LIBRARY_PATH                 : /opt/tritonserver/lib:/opt/tritonclient/lib:/usr/src/tensorrt/lib:/opt/riva/lib:/usr/local/cuda-13/lib64:/usr/lib/x86_64-linux-gnu:/opt/hpcx/ucc/lib/:/opt/hpcx/ucx/lib/:/usr/local/cuda/compat/lib:/usr/local/nvidia/lib:/usr/local/nvidia/lib64:/.local/lib
 NUMBAPRO_NVVM                   :
 NUMBAPRO_LIBDEVICE              :
 CONDA_PREFIX                    :
 PYTHON_PATH                     :
 
 conda not found
 ***pip packages***
 /usr/bin/pip
 Package             Version
 ------------------- ---------------
 annotated-doc       0.0.4
 annotated-types     0.7.0
 anyio               4.12.1
 apparmor            4.0.1
 certifi             2026.2.25
 cupy-cuda13x        13.6.0
 distlib             0.4.0
 distro              1.9.0
 fastapi             0.138.1
 fastrlock           0.8.3
 filelock            3.25.2
 h11                 0.16.0
 httpcore            1.0.9
 httpx               0.27.2
 idna                3.11
 iniconfig           2.3.0
 jaraco.context      6.1.0
 jiter               0.13.0
 LibAppArmor         4.0.1
 numpy               1.26.4
 openai              1.107.3
 packaging           24.0
 partial-json-parser 0.2.1.1.post7
 pip                 24.0
 platformdirs        4.9.4
 pluggy              1.6.0
 pydantic            2.10.6
 pydantic_core       2.27.2
 Pygments            2.19.2
 pyservicemaker      0.0.1
 pytest              9.0.2
 python-apt          2.7.7+ubuntu5.2
 python-discovery    1.1.3
 scipy               1.16.3
 setuptools          78.1.1
 sniffio             1.3.1
 starlette           0.52.1
 tqdm                4.67.3
 tritonfrontend      2.67.0
 tritonserver        0.0.0
 typing_extensions   4.15.0
 typing-inspection   0.4.2
 virtualenv          21.2.0
 wheel               0.42.0

Additional context

The segfault ends the process with no Python traceback unless faulthandler is enabled, so in a service it looks like a crash with no cause. The aarch64 branch of Buffer::extract() has the same nullptr return for non-RGB surfaces.

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2 Std. 24 Min.
Gemergte PRs (30 T.)
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