Fix OOM state-desync in generated array-member setters - #2414
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The generated setters for list-valued struct members (CUlaunchConfig.attrs,
CUDA_MEM_ALLOC_NODE_PARAMS.accessDescs, ...) freed the old buffer, then
allocated the new one; on allocation failure they raised *before* updating
the cached length and the C-struct pointer. That left the wrapper with a
freed buffer but a stale length and a dangling _pvt_ptr[0].<m>:
- a later same-length assignment took the no-resize path and memcpy'd
through the freed/NULL buffer -> near-NULL segfault, and
- getPtr()-then-CUDA read the dangling pointer -> use-after-free.
The setters now allocate and fill a new buffer first, and free/swap the old
one only once the resize is known to succeed, so a failed (over)allocation
leaves the object completely unchanged (strong exception guarantee).
The fix is made in the cybind generator template (legacy_cython_gen). These
files are the full regenerated output of
python -m cybind --generate-module "cuda.*" \
--output-dir <checkout>/cuda_bindings --ctk-target-version 13.3
so besides the setter change (18 driver + 11 runtime setters) the regen also
picks up accumulated docstring-only cleanups that have landed in cybind since
the last sync (no API/behavior change). Adds a subprocess regression test that
forces the failed resize via an overflowing __len__.
Addresses Glasswing finding V1.1 (NVBUG 6268871).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Jul 23, 2026
| CUDA_EMULATION_STRATEGY_EAGER | ||
| ctypedef cudaEmulationStrategy_t cudaEmulationStrategy | ||
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| cdef extern from 'library_types.h': |
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Looks like maybe there is a non-deterministic ordering bug in the generator here. Not to fix now, but I will file a bug over there.
| self._pvt_ptr[0].paramsArray = _paramsArray_new | ||
| else: | ||
| for idx in range(len(val)): | ||
| string.memcpy(&self._paramsArray[idx], (<cudaExternalSemaphoreWaitParams>val[idx])._pvt_ptr, sizeof(cyruntime.cudaExternalSemaphoreWaitParams)) |
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We really should refactor this out into a function to remove all this duplication, but the legacy generator makes that hard and probably not worth the effort for something that's being deprecated.
mdboom
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Closing as superseded by #2423. The setter fix in this PR already landed on This branch is a CTK 13.3 regen, so rebasing it onto 13.4 |
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Summary
The generated setters for list-valued struct members (
CUlaunchConfig.attrs,CUDA_MEM_ALLOC_NODE_PARAMS.accessDescs, and ~27 siblings) freed the old heap buffer before allocating the new one. On an allocation failure they raisedMemoryErrorbefore updating the cached length and the C-struct pointer, leaving the wrapper with a freed buffer but a stale length and a dangling_pvt_ptr[0].<m>:memcpy'd through the freed/NULL buffer -> near-NULL segfault, andgetPtr()-then-CUDA read the dangling pointer -> use-after-free.Fix
Allocate and fill the new buffer first, and free/swap the old one only once the resize is known to succeed -- a strong exception guarantee. A failed (over)allocation now leaves the object completely unchanged.
Regeneration
The change is in the cybind generator template (
legacy_cython_gen); this PR is the full regenerated output of:Besides the setter fix (18
driver+ 11runtimesetters), the regen also picks up docstring-only cleanups that have landed in cybind since the last sync (e.g.nvml.pyx,runtime.pxd,cyruntime.pxd,runtime.rst). These are formatting-only -- no API, signature, or behavior changes -- and are included because they are part of what the canonical regeneration command produces.Verification
test_array_setter_preserves_state_on_failed_resizeforces the failed resize via an overflowing__len__(socallocoverflowssize_t-> NULL, no real host OOM needed). Passes; the two existing Fix a double-free bug #2112 array-setter regression tests still pass.Context
Addresses NVBUG 6268871. Companion cybind template change is under review separately; this PR exists so the regenerated bindings get full CI.