{"id":"CVE-2026-90136","revision":"c5d86ead1376413385e78acf8a29c49b","records":[{"revision":"c5d86ead1376413385e78acf8a29c49b","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-90136","aliases":[],"title":"platform/x86/amd/hsmp: Reject negative power cap writes in hwmon","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86/amd/hsmp: Reject negative power cap writes in hwmon\n\nhsmp_hwmon_write() takes the user-supplied hwmon value as a signed long\nand assigns \"val / MICROWATT_PER_MILLIWATT\" to msg.args[0], which is a\n__u32.  MICROWATT_PER_MILLIWATT is an unsigned long, so a negative write\nto power1_cap (e.g. \"echo -1 > power1_cap\") is first converted to a huge\nunsigned value by the division and then stored into the u32 argument.\n\nAs a result a nonsensical, multi-gigawatt socket power limit is sent to\nthe SMU via HSMP_SET_SOCKET_POWER_LIMIT instead of the write being\nrejected.\n\nReject negative values with -EINVAL before the conversion.\n\nTested with HSMP enabled:\n\n  CAP=$(dirname $(grep -l amd_hsmp_hwmon \\\n        /sys/class/hwmon/hwmon*/name | head -1))/power1_cap\n\n  # negative write\n  echo -1000000 > $CAP ; echo \"ret=$?\"\n  # valid positive write must still work\n  echo 400000000 > $CAP ; echo \"ret=$?\"\n\nBefore:\n  # echo -1000000 > $CAP ; echo \"ret=$?\"\n  ret=0                             <- accepted; bogus limit sent to SMU\n  # echo 400000000 > $CAP ; echo \"ret=$?\"\n  ret=0\n\nAfter:\n  # echo -1000000 > $CAP ; echo \"ret=$?\"\n  bash: echo: write error: Invalid argument\n  ret=1                             <- rejected with -EINVAL\n  # echo 400000000 > $CAP ; echo \"ret=$?\"\n  ret=0                             <- valid write still works","state":0,"publishedAt":"2026-09-17T16:06:35.19+00:00","modifiedAt":"2026-10-19T08:58:34.349+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"drivers/platform/x86/amd/hsmp/hwmon.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"92c025db52bb94a032eb3d473bb81e62c19ddbd3\",\n                            \"lessThan\": \"2c09cadec116eba3fdbcb5d8d8641f6777d4a11f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"92c025db52bb94a032eb3d473bb81e62c19ddbd3\",\n                            \"lessThan\": \"1b0a3d915320f1600e5ff43f8bc21b73118480b8\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"92c025db52bb94a032eb3d473bb81e62c19ddbd3\",\n                            \"lessThan\": \"3921bb8635ff2836622df1cdf3194d4f3c1835a4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"drivers/platform/x86/amd/hsmp/hwmon.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.16\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.16\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.52\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.6\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/2c09cadec116eba3fdbcb5d8d8641f6777d4a11f","https://git.kernel.org/stable/c/1b0a3d915320f1600e5ff43f8bc21b73118480b8","https://git.kernel.org/stable/c/3921bb8635ff2836622df1cdf3194d4f3c1835a4"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-90136","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-90136","identifiers":["CVE-2026-90136"]},"retained":false,"historicalAffected":[]}],"coverage":[]}