CVE-2026-89801drm/nouveau/uvmm: fix premature region free on failed OP_UNMAP_SPARSE

Official description

In the Linux kernel, the following vulnerability has been resolved: drm/nouveau/uvmm: fix premature region free on failed OP_UNMAP_SPARSE In nouveau_uvmm_bind_job_submit()'s OP_UNMAP_SPARSE arm, op->reg is set from nouveau_uvma_region_find(), which only looks the region up and takes no reference; a region's sole reference is its membership in uvmm->region_mt. Two failure paths leave op->reg set: the -ENOENT check when the region is busy, and the drm_gpuvm_sm_unmap_ops_create() failure. The sibling nouveau_uvmm_sm_unmap_prepare() failure just below clears op->reg; these two do not. unwind_continue steps back one op, so the failing op is skipped by the unwind loop and its op->reg stays set. nouveau_uvmm_bind_job_cleanup() then enters its if (op->reg) branch and calls nouveau_uvma_region_remove() and nouveau_uvma_region_put() on it, dropping the tree's sole reference and freeing a region this job never created. The comment above the cleanup loop documents the broken invariant: op->reg must be NULL on submit failure. This frees a live region on an unrelated failure, reachable single-job when drm_gpuvm_sm_unmap_ops_create() returns -ENOMEM; if another job owns the same region, its cleanup then removes and puts the freed region, a use-after-free. Clear op->reg on both failure paths.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/ba42d8a1c2c7629c61914df11a7d63ac77449ffb
• https://git.kernel.org/stable/c/88114e3a96582882e63b2f73aa7a5a9cf0d5073c
• https://git.kernel.org/stable/c/24c25b182d17d1bdfde0088c96bdf6f93e8f46bc
• https://git.kernel.org/stable/c/4083d24c2636fde7b18076115af52820d203bc57
• https://git.kernel.org/stable/c/ccf930812f23b8259ef64fd3394d53b093e4651a