In the Linux kernel, the following vulnerability has been resolved:
drm/amdkfd: Don't call mmput from MMU notifier callback
If the process is exiting, the mmput inside mmu notifier callback from
compactd or fork or numa balancing could release the last reference
of mm struct to call exit_mmap and free_pgtable, this triggers deadlock
with below backtrace.
The deadlock will leak kfd process as mmu notifier release is not called
and cause VRAM leaking.
The fix is to take mm reference mmget_non_zero when adding prange to the
deferred list to pair with mmput in deferred list work.
If prange split and add into pchild list, the pchild work_item.mm is not
used, so remove the mm parameter from svm_range_unmap_split and
svm_range_add_child.
The backtrace of hung task:
INFO: task python:348105 blocked for more than 64512 seconds.
Call Trace:
__schedule+0x1c3/0x550
schedule+0x46/0xb0
rwsem_down_write_slowpath+0x24b/0x4c0
unlink_anon_vmas+0xb1/0x1c0
free_pgtables+0xa9/0x130
exit_mmap+0xbc/0x1a0
mmput+0x5a/0x140
svm_range_cpu_invalidate_pagetables+0x2b/0x40 [amdgpu]
mn_itree_invalidate+0x72/0xc0
__mmu_notifier_invalidate_range_start+0x48/0x60
try_to_unmap_one+0x10fa/0x1400
rmap_walk_anon+0x196/0x460
try_to_unmap+0xbb/0x210
migrate_page_unmap+0x54d/0x7e0
migrate_pages_batch+0x1c3/0xae0
migrate_pages_sync+0x98/0x240
migrate_pages+0x25c/0x520
compact_zone+0x29d/0x590
compact_zone_order+0xb6/0xf0
try_to_compact_pages+0xbe/0x220
__alloc_pages_direct_compact+0x96/0x1a0
__alloc_pages_slowpath+0x410/0x930
__alloc_pages_nodemask+0x3a9/0x3e0
do_huge_pmd_anonymous_page+0xd7/0x3e0
__handle_mm_fault+0x5e3/0x5f0
handle_mm_fault+0xf7/0x2e0
hmm_vma_fault.isra.0+0x4d/0xa0
walk_pmd_range.isra.0+0xa8/0x310
walk_pud_range+0x167/0x240
walk_pgd_range+0x55/0x100
__walk_page_range+0x87/0x90
walk_page_range+0xf6/0x160
hmm_range_fault+0x4f/0x90
amdgpu_hmm_range_get_pages+0x123/0x230 [amdgpu]
amdgpu_ttm_tt_get_user_pages+0xb1/0x150 [amdgpu]
init_user_pages+0xb1/0x2a0 [amdgpu]
amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu+0x543/0x7d0 [amdgpu]
kfd_ioctl_alloc_memory_of_gpu+0x24c/0x4e0 [amdgpu]
kfd_ioctl+0x29d/0x500 [amdgpu]
(cherry picked from commit a29e067bd38946f752b0ef855f3dfff87e77bec7)
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.1% 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
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA 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 SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
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