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CVE-2026-68329— iommu/amd: Wait for completion instead of returning early in iommu_completion_wait()

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基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于drivers/iommu/amd/iommu.c文件中的iommu_completion_wait()函数在need_sync为false时提前返回，未能等待先前排队的命令完成，可能导致释放后重用。

CVSS 8.8 · High EPSS 0.16% · P5

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux 815b33fdc279d34ab40a8bfe1866623a4cc5669b< ab7faf5a172ebfdc423ebb3eea4d472740de82f9 affected
815b33fdc279d34ab40a8bfe1866623a4cc5669b< 93494bd446396c257fb589f59894577e96e406e2 affected
815b33fdc279d34ab40a8bfe1866623a4cc5669b< d053eb7e09e10cbdca3fca8b35c1017d438091b2 affected
815b33fdc279d34ab40a8bfe1866623a4cc5669b< 02f8cefa2ad95ea3754f0cfd6fbae7f866202ccb affected
815b33fdc279d34ab40a8bfe1866623a4cc5669b< 1e75a8255f11c81fb07e81e5029cfd75804350a0 affected
3.0 affected
< 3.0 unaffected
6.6.148≤ 6.6.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-68329

Vulnerability Information
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Vulnerability Title
iommu/amd: Wait for completion instead of returning early in iommu_completion_wait()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: iommu/amd: Wait for completion instead of returning early in iommu_completion_wait() need_sync is a per-IOMMU flag shared by all domains and devices behind that IOMMU. It is set whenever a command is queued with sync == true and cleared when a completion-wait (CWAIT) command is queued. However, a cleared need_sync only means that a covering CWAIT has been queued, not that all previously queued commands have actually completed in hardware. iommu_completion_wait() read need_sync locklessly and returned early when it was false. This breaks the "block until all previously queued commands have completed" contract in a multi-CPU scenario: CPU2: queue inv-B => need_sync = true CPU1: queue CWAIT(N); need_sync = false; then wait_on_sem(N) CPU2: read need_sync == false => return 0 (no wait!) CPU2 returns without waiting for any sequence number even though its inv-B may not have completed yet (CWAIT(N), queued after inv-B, has not been signaled). CPU2 then proceeds to, for example, free page-table pages while the IOMMU can still walk stale translations, opening a use-after-free window. This is a logical race in the meaning of the flag, not a memory-visibility issue, so barriers alone do not help. Fix it without losing the optimization of avoiding redundant CWAIT commands: take iommu->lock before testing need_sync, and when it is false do not return early but wait for the last allocated sequence number (cmd_sem_val). Since need_sync == false implies no sync command was queued after the last CWAIT, that CWAIT is FIFO-ordered after every not-yet-completed command, so waiting for its sequence number guarantees all prior commands (possibly queued by another CPU) have completed. The common path with pending work is unchanged and no extra hardware command is issued.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
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基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于drivers/iommu/amd/iommu.c文件中的iommu_completion_wait()函数在need_sync为false时提前返回，未能等待先前排队的命令完成，可能导致释放后重用。
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 815b33fdc279d34ab40a8bfe1866623a4cc5669b ~ ab7faf5a172ebfdc423ebb3eea4d472740de82f9 -
Linux Linux 3.0 -

II. Public POCs for CVE-2026-68329

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III. Intelligence Information for CVE-2026-68329

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Patches & Fixes for CVE-2026-68329 (5)

Same Patch Batch · Linux · 2026-08-10 · 344 CVEs total

CVE-2026-68161 9.8 CRITICAL sctp: close UDP tunnel sockets during netns teardown
CVE-2026-68123 9.8 CRITICAL openvswitch: fix GSO userspace truncation underflow
CVE-2026-68127 9.8 CRITICAL ila: reload IPv6 header after pskb_may_pull in checksum adjust
CVE-2026-68117 9.8 CRITICAL tipc: clear sock->sk on the failed-insert path in tipc_sk_create()
CVE-2026-68136 9.8 CRITICAL net: gro: fix double aggregation of flush-marked skbs
CVE-2026-68137 9.8 CRITICAL net/x25: fix use-after-free in x25_kill_by_neigh()
CVE-2026-68300 9.8 CRITICAL sctp: auth: verify auth requirement when auth_chunk is NULL
CVE-2026-68144 9.8 CRITICAL phonet: pep: fix use-after-free in pep_get_sb()
CVE-2026-68154 9.8 CRITICAL libceph: reject zero bucket types in crush_decode
CVE-2026-68156 9.8 CRITICAL libceph: refresh auth->authorizer_buf{,_len} after authorizer update
CVE-2026-68158 9.8 CRITICAL libceph: Fix multiplication overflow in decode_new_up_state_weight()
CVE-2026-68159 9.8 CRITICAL libceph: bound pg_{temp,upmap,upmap_items} length to CEPH_PG_MAX_SIZE
CVE-2026-68160 9.8 CRITICAL ceph: fix pre-auth out-of-bounds read on snaptrace in ceph_handle_caps()
CVE-2026-68302 9.8 CRITICAL amt: re-read skb header pointers after every pull
CVE-2026-68170 9.8 CRITICAL mptcp: fix stale skb->sk reference on subflow close
CVE-2026-68381 9.8 CRITICAL ksmbd: pin conn during async oplock break notification
CVE-2026-68385 9.8 CRITICAL s390/checksum: Fix csum_partial() without vector facility
CVE-2026-68388 9.8 CRITICAL smb/client: handle overlapping allocated ranges in fallocate
CVE-2026-68426 9.8 CRITICAL xfrm: fix stale skb->prev after async crypto steals a GSO segment
CVE-2026-68124 9.6 CRITICAL mctp: serial: handle zero-length frames to prevent rx buffer overflow

Showing top 20 of 344 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-68329

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