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CVE-2026-64590— dma-buf/udmabuf: skip redundant cpu sync to fix cacheline EEXIST warning

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 5.6版本存在安全漏洞，该漏洞源于udmabuf在DMA映射时未跳过冗余CPU同步，导致缓存行重叠映射，可能触发内核警告。

AI Predicted 5.3 Difficulty: Trivial EPSS 0.17% · P6

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 284562e1f34874e267d4f499362c3816f8f6bc3f< 4a7c644e632741c2a3116a0d3da6c11de957a6ba affected
284562e1f34874e267d4f499362c3816f8f6bc3f< 01126abc11bcc6a45b664293b0b5df715be911d7 affected
284562e1f34874e267d4f499362c3816f8f6bc3f< dd7f1e572f44d3d039dc77e3989f537196c3bf52 affected
284562e1f34874e267d4f499362c3816f8f6bc3f< 0db56e7eae932f8e2f3eb44ad1a63633d8f504f8 affected
284562e1f34874e267d4f499362c3816f8f6bc3f< d6552f5cff795d60e629f37513ecf23d88fd2f82 affected
284562e1f34874e267d4f499362c3816f8f6bc3f< 34696563461c9a23177feb6d8aff43f4c0510278 affected
284562e1f34874e267d4f499362c3816f8f6bc3f< 0449a6583c0ee76778d314e4e82f166fc97fa9d8 affected
284562e1f34874e267d4f499362c3816f8f6bc3f< 504e2b4ab97a51d56d966cd36d0997ad30b65b2d affected
… +10 more rows
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I. Basic Information for CVE-2026-64590

Vulnerability Information
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Vulnerability Title
dma-buf/udmabuf: skip redundant cpu sync to fix cacheline EEXIST warning
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: dma-buf/udmabuf: skip redundant cpu sync to fix cacheline EEXIST warning When CONFIG_DMA_API_DEBUG_SG is enabled, importing a udmabuf into a DRM driver (e.g. amdgpu for video playback in GNOME Videos / Showtime) triggers a spurious warning: DMA-API: amdgpu 0000:03:00.0: cacheline tracking EEXIST, \ overlapping mappings aren't supported WARNING: kernel/dma/debug.c:619 at add_dma_entry+0x473/0x5f0 The call chain is: amdgpu_cs_ioctl -> amdgpu_ttm_backend_bind -> dma_buf_map_attachment -> [udmabuf] map_udmabuf -> get_sg_table -> dma_map_sgtable(dev, sg, direction, 0) // attrs=0 -> debug_dma_map_sg -> add_dma_entry -> EEXIST This happens because udmabuf builds a per-page scatter-gather list via sg_set_folio(). When begin_cpu_udmabuf() has already created an sg table mapped for the misc device, and an importer such as amdgpu maps the same pages for its own device via map_udmabuf(), the DMA debug infrastructure sees two active mappings whose physical addresses share cacheline boundaries and warns about the overlap. The DMA_ATTR_SKIP_CPU_SYNC flag suppresses this check in add_dma_entry() because it signals that no CPU cache maintenance is performed at map/unmap time, making the cacheline overlap harmless. All other major dma-buf exporters already pass this flag: - drm_gem_map_dma_buf() passes DMA_ATTR_SKIP_CPU_SYNC - amdgpu_dma_buf_map() passes DMA_ATTR_SKIP_CPU_SYNC The CPU sync at map/unmap time is also redundant for udmabuf: begin_cpu_udmabuf() and end_cpu_udmabuf() already perform explicit cache synchronization via dma_sync_sgtable_for_cpu/device() when CPU access is requested through the dma-buf interface. Pass DMA_ATTR_SKIP_CPU_SYNC to dma_map_sgtable() and dma_unmap_sgtable() in udmabuf to suppress the spurious warning and skip the redundant sync.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 5.6版本存在安全漏洞，该漏洞源于udmabuf在DMA映射时未跳过冗余CPU同步，导致缓存行重叠映射，可能触发内核警告。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 284562e1f34874e267d4f499362c3816f8f6bc3f ~ 4a7c644e632741c2a3116a0d3da6c11de957a6ba -
Linux Linux 5.6 -

II. Public POCs for CVE-2026-64590

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III. Intelligence Information for CVE-2026-64590

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Patches & Fixes for CVE-2026-64590 (6)

Other References for CVE-2026-64590 (1)

Same Patch Batch · Linux · 2026-08-06 · 22 CVEs total

CVE-2026-64597 9.8 CRITICAL smb: client: fix double-free in SMB2_close() replay
CVE-2026-64586 8.8 HIGH wifi: brcmfmac: drain bus_reset work on device removal
CVE-2026-64598 8.8 HIGH smb/client: Fix error code in smb2_aead_req_alloc()
CVE-2026-64584 7.8 HIGH usb: gadget: f_midi: cancel pending IN work before freeing the midi object
CVE-2026-64585 7.8 HIGH can: esd_usb: kill anchored URBs before freeing netdevs
CVE-2026-64588 7.8 HIGH fuse-uring: fix data races on ring->ready
CVE-2026-64583 7.8 HIGH usb: gadget: udc: bdc: free IRQ and drain func_wake_notify before teardown
CVE-2026-64601 7.8 HIGH ALSA: us144mkii: capture_urb_complete: redundant usb_anchor_urb corrupts anchor list on ea
CVE-2026-64599 7.8 HIGH crypto: amlogic - avoid double cleanup in meson_crypto_probe()
CVE-2026-64587 7.0 HIGH net: ethernet: arc: emac: quiesce interrupts before requesting IRQ
CVE-2026-68480 x86/bugs: Make Safe-RET robust against interrupt injection
CVE-2026-64604 KVM: VMX: Grab vmcs12 on CR8 interception update iff vCPU is in guest mode
CVE-2026-64603 platform/x86: intel-hid: Protect ACPI notify handler against recursion
CVE-2026-64602 iio: adc: spear: Initialize completion before requesting IRQ
CVE-2026-64596 libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo()
CVE-2026-64595 HID: hid-lenovo-go: cancel cfg_setup work in hid_go_cfg_remove()
CVE-2026-64593 btrfs: do not trim a device which is not writeable
CVE-2026-64594 usb: gadget: f_fs: initialize reset_work at allocation time
CVE-2026-64592 riscv: mm: Unconditionally sfence.vma for spurious fault
CVE-2026-64591 iommu/vt-d: Avoid WARNING in sva unbind path

Showing top 20 of 22 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-64590

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