In the Linux kernel, the following vulnerability has been resolved:
drm/imagination: Fix reference and vm_bo handling in remap()
When a map overlaps part of an existing mapping, pvr_vm_gpuva_remap()
splits the mapping into prev/next parts covering what the request did
not take, instead of creating something new. It gets two things wrong.
- A GEM reference is taken for each part but it's never needed and never
dropped, so it leaks one reference per split (remap-next-in-2m in
tests/imagination/pvr_vm_map.c):
CRITICAL: 33558528 bytes of shmem still held after close
- The parts still belong to the original object being split, but
pvr_vm_gpuva_remap() links them to ctx->gpuvm_bo, the new object's
vm_bo:
prev_va --obj--> BO_A BO_B <--obj-- vm_bo (ctx->gpuvm_bo)
\___________link___________/ (mismatch: BO_A != BO_B)
drm_gpuva_link() catches the mismatch:
WARNING: drivers/gpu/drm/drm_gpuvm.c:2108 at drm_gpuva_link+0x2ec/0x310
drm_WARN_ON(obj != vm_bo->obj)
Call trace:
drm_gpuva_link
pvr_vm_gpuva_remap
__drm_gpuvm_sm_map
pvr_vm_map
pvr_ioctl_vm_map
Link them to op->remap.unmap->va->vm_bo instead.
The locking of the GPUVA lists of the other objects touched by a split is
not addressed here; it is handled by switching the GPUVM to immediate
mode.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
- EG Severity
- Not assessed: no CVSS publishedA missing CVSS is not a severity of zero.
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- No SSVC decision: EchelonGraph has not assessed this CVECISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the BOD 26-04 block below.
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it