{"id":"CVE-2026-64293","revision":"038b248738184cd5a810ab9e649d9507","records":[{"revision":"038b248738184cd5a810ab9e649d9507","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-64293","aliases":[],"title":"iommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read","description":"In the Linux kernel, the following vulnerability has been resolved:\n\niommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read\n\nThe bound-check in iommufd_veventq_fops_read() for the normal vEVENT\npath uses sizeof(hdr) where the surrounding code uses sizeof(*hdr):\n\n\tif (!vevent_for_lost_events_header(cur) &&\n\t    sizeof(hdr) + cur->data_len > count - done) {\n\nhdr is declared as struct iommufd_vevent_header *, so sizeof(hdr)\nevaluates to the size of the pointer.  Surrounding code uses\nsizeof(*hdr) consistently:\n\n\tif (done >= count || sizeof(*hdr) > count - done) {\n\t...\n\tif (copy_to_user(buf + done, hdr, sizeof(*hdr))) {\n\t...\n\tdone += sizeof(*hdr);\n\nstruct iommufd_vevent_header is currently 8 bytes (two __u32 fields,\nflags and sequence), so on 64-bit (sizeof(void *) == 8) the two\nexpressions happen to be equal and the check works as intended.\n\nOn 32-bit (sizeof(void *) == 4) the check under-counts the header by\n4 bytes: a vEVENT whose data_len causes 8 + cur->data_len to exceed\ncount - done while 4 + cur->data_len does not will pass the check,\nthen the loop will copy_to_user 8 bytes of header followed by data_len\nbytes of payload, writing past the user-supplied buffer.\n\nIt is also a latent bug for any future expansion of struct\niommufd_vevent_header beyond sizeof(void *) on 64-bit; the check\nshould not depend on the type happening to match the host pointer\nwidth.\n\nUse sizeof(*hdr) to match the rest of the function and the actual\namount that will be copied.","state":0,"publishedAt":"2026-07-25T08:49:31.945+00:00","modifiedAt":"2026-10-19T20:38:22.244+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/iommu/iommufd/eventq.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"e36ba5ab808ef6237c3148d469c8238674230e2b\",\n                            \"lessThan\": \"04a177f91160ee18da98f5689482cf0f589ec869\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e36ba5ab808ef6237c3148d469c8238674230e2b\",\n                            \"lessThan\": \"0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e36ba5ab808ef6237c3148d469c8238674230e2b\",\n                            \"lessThan\": \"be93d186ae88a92e7aa77e122d4e661fa57b1e39\",\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/iommu/iommufd/eventq.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.15\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.15\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.39\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1.4\",\n                            \"lessThanOrEqual\": \"7.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/04a177f91160ee18da98f5689482cf0f589ec869","https://git.kernel.org/stable/c/0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72","https://git.kernel.org/stable/c/be93d186ae88a92e7aa77e122d4e661fa57b1e39"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64293","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-64293","identifiers":["CVE-2026-64293"]},"retained":false,"historicalAffected":[]}],"coverage":[]}