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CVE-2026-90136— platform/x86/amd/hsmp: Reject negative power cap writes in hwmon

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.

在 Linux 内核中，以下漏洞已得到修复： platform/x86/amd/hsmp：在 hwmon 中拒绝负的电源限制写入 将用户提供的 hwmon 值作为有符号 long 类型处理，并将 赋值给 （其类型为 ）。由于 是无符号 long 类型，向 （例如 ）写入负值时，该负值会先通过除法转换为一个极大的无符号数值，然后被存储到 u32 参数中。 结果是，一个毫无意义的、达数吉瓦级的插槽功率限制值会被通过 命令发送给 SMU（系统管理单元），而不是拒绝该写入操作。 修复方案： 在数值转换之前，使用 拒绝负值。

AI Predicted 3.1 Difficulty: Theoretical EPSS 0.21% · P10

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 92c025db52bb94a032eb3d473bb81e62c19ddbd3< 2c09cadec116eba3fdbcb5d8d8641f6777d4a11f affected
92c025db52bb94a032eb3d473bb81e62c19ddbd3< 1b0a3d915320f1600e5ff43f8bc21b73118480b8 affected
92c025db52bb94a032eb3d473bb81e62c19ddbd3< 3921bb8635ff2836622df1cdf3194d4f3c1835a4 affected
6.16 affected
< 6.16 unaffected
6.18.52≤ 6.18.* unaffected
7.2.6≤ 7.2.* unaffected
7.3-rc1≤ * unaffected
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I. Basic Information for CVE-2026-90136

Vulnerability Information
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Vulnerability Title
platform/x86/amd/hsmp: Reject negative power cap writes in hwmon
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: platform/x86/amd/hsmp: Reject negative power cap writes in hwmon hsmp_hwmon_write() takes the user-supplied hwmon value as a signed long and assigns "val / MICROWATT_PER_MILLIWATT" to msg.args[0], which is a __u32. MICROWATT_PER_MILLIWATT is an unsigned long, so a negative write to power1_cap (e.g. "echo -1 > power1_cap") is first converted to a huge unsigned value by the division and then stored into the u32 argument. As a result a nonsensical, multi-gigawatt socket power limit is sent to the SMU via HSMP_SET_SOCKET_POWER_LIMIT instead of the write being rejected. Reject negative values with -EINVAL before the conversion. Tested with HSMP enabled: CAP=$(dirname $(grep -l amd_hsmp_hwmon \ /sys/class/hwmon/hwmon*/name | head -1))/power1_cap # negative write echo -1000000 > $CAP ; echo "ret=$?" # valid positive write must still work echo 400000000 > $CAP ; echo "ret=$?" Before: # echo -1000000 > $CAP ; echo "ret=$?" ret=0 <- accepted; bogus limit sent to SMU # echo 400000000 > $CAP ; echo "ret=$?" ret=0 After: # echo -1000000 > $CAP ; echo "ret=$?" bash: echo: write error: Invalid argument ret=1 <- rejected with -EINVAL # echo 400000000 > $CAP ; echo "ret=$?" ret=0 <- valid write still works
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

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 92c025db52bb94a032eb3d473bb81e62c19ddbd3 ~ 2c09cadec116eba3fdbcb5d8d8641f6777d4a11f -
Linux Linux 6.16 -

II. Public POCs for CVE-2026-90136

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III. Intelligence Information for CVE-2026-90136

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Patches & Fixes for CVE-2026-90136 (3)

Same Patch Batch · Linux · 2026-09-17 · 600 CVEs total

CVE-2026-90235 9.8 CRITICAL sunrpc: xprtsock: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE
CVE-2026-90104 9.8 CRITICAL NFSv4.1: zero referring call lists before decoding
CVE-2026-92489 9.8 CRITICAL xfrm: Fix skb double-free in xfrm_dev_direct_output()
CVE-2026-90173 9.8 CRITICAL smb: smbdirect: free completion queues with ib_free_cq()
CVE-2026-90151 9.8 CRITICAL NFSv4: remove callback IDR entry on client allocation failure
CVE-2026-90110 9.4 CRITICAL inetpeer: randomize RB-tree node comparison using SipHash
CVE-2026-90230 9.1 CRITICAL nvmet: fix heap out-of-bounds read in nvmet_auth_negotiate()
CVE-2026-90414 9.1 CRITICAL IB/isert: reject PDUs declaring more data than was received
CVE-2026-90413 9.1 CRITICAL IB/isert: reject login PDUs declaring more data than was received
CVE-2026-93189 8.8 HIGH HID: core: quiesce input in hid_hw_stop() to prevent use-after-free
CVE-2026-90256 8.8 HIGH Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind
CVE-2026-93042 8.8 HIGH dmaengine: dw-edma: Terminate all descriptors without callbacks
CVE-2026-90286 8.8 HIGH drm/amdgpu/gfx6: Use PFP on the compute queues too
CVE-2026-90255 8.8 HIGH Bluetooth: hci_conn: fix the SCO setup context lifetime
CVE-2026-90425 8.8 HIGH iommu/tegra241-cmdqv: Require exactly one Stream ID for a vSID
CVE-2026-90329 8.8 HIGH HID: synchronize input before cleaning up a failed probe
CVE-2026-90162 8.8 HIGH ksmbd: defer publishing granted locks to prevent UAF/double-free race
CVE-2026-90240 8.8 HIGH iommu/vt-d: Flush context cache with correct SID when tearing down aliases
CVE-2026-90367 8.8 HIGH wifi: mt76: mt7996: hold dev->mt76.mutex while disabling tx worker in SER
CVE-2026-90371 8.8 HIGH wifi: mt76: fix RXDMAD_C buffer recycling race

Showing top 20 of 600 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-90136

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