{"id":"AZL-100400","summary":"CVE-2026-89665 affecting package kernel 6.6.150.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: reject out-of-range useconds in NFSv2 SETATTR/CREATE\n\nThe NFSv2 sattr decoder converts the wire useconds to nanoseconds in\nsvcxdr_decode_sattr():\n\n\tiap-\u003eia_atime.tv_nsec = tmp2 * NSEC_PER_USEC;\n\ntmp2 is a u32 and NSEC_PER_USEC is 1000, so the product is computed in\nunsigned long. On ILP32 that is 32 bits, and an out-of-range useconds\nvalue such as 4294968 wraps to tv_nsec == 704. The corruption therefore\nhappens during decode, before any proc function can inspect the value,\nand a later range check on tv_nsec would see an in-range result and\naccept it. Rejecting in the decoder yields an RPC GARBAGE_ARGS reply.\nNFSv2 defines no NFSERR_INVAL, so there is no NFS-level status to return\nfor a malformed time argument, and the check cannot move to the proc\nfunction the way the v3/v4 nsec range checks do.\n\nGuard the raw useconds before the multiplication and reject values\ngreater than 1000000. useconds == 1000000 is kept: it is the Sun\nconvention for \"set to the current server time\", and the in-tree Linux\nNFSv2 client emits it in both the atime and the mtime field for a plain\ntouch / utimes(file, NULL) (see encode_sattr() and\nxdr_encode_current_server_time() in fs/nfs/nfs2xdr.c). Rejecting 1000000\nwould turn that common operation into a hard decode failure for both\nSETATTR and CREATE. 1000000 * NSEC_PER_USEC is 10^9, which does not wrap\non ILP32, so the Sun convention value passes through safely. Only\ngenuinely out-of-range values (\u003e 1000000) are rejected. The atime and\nmtime guards are therefore symmetric.\n\nThe decoder only applied the Sun convention in the mtime block, which\nclears ATTR_ATIME_SET|ATTR_MTIME_SET when mtime useconds == 1000000. If a\nclient puts 1000000 in the atime field but not in the mtime field, the\natime block stored an out-of-range tv_nsec (10^9) and left ATTR_ATIME_SET\nset, so the bogus value reached the filesystem. Apply the convention in\nthe atime block as well, clearing ATTR_ATIME_SET so the server uses its\ncurrent time and ignores the value. Only ATTR_ATIME_SET is cleared there.\nThe mtime block keeps its existing behavior, where 1000000 means \"set\nboth atime and mtime to now\".\n\n[ cel: various tweaks, addenda, and clean-ups ]","modified":"2026-09-13T06:06:36Z","published":"2026-09-11T20:19:52Z","upstream":["CVE-2026-89665"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89665"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.150.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-100400.json"}}],"schema_version":"1.9.0"}