{"id":"CVE-2026-98366","summary":"RDMA/rxe: validate access flags before swapping the MR's PD","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/rxe: validate access flags before swapping the MR's PD\n\nrxe_rereg_user_mr() reassigns mr-\u003eibmr.pd first and only then\nvalidates the IB_MR_REREG_ACCESS argument:\n\n\tif (flags & IB_MR_REREG_PD) {\n\t\trxe_put(old_pd);\n\t\trxe_get(pd);\n\t\tmr-\u003eibmr.pd = ibpd;\n\t}\n\n\tif (flags & IB_MR_REREG_ACCESS) {\n\t\tif (access & ~RXE_ACCESS_SUPPORTED_MR)\n\t\t\treturn ERR_PTR(-EOPNOTSUPP);\n\t\tmr-\u003eaccess = access;\n\t}\n\nBoth flags pass the entry check because RXE_MR_REREG_SUPPORTED is\nIB_MR_REREG_PD | IB_MR_REREG_ACCESS, so a caller can reach the access\ncheck with mr-\u003eibmr.pd already reassigned.\n\nmr-\u003eibmr.pd is owned by the core, which adjusts pd-\u003eusecnt only on the\nsuccess path: ib_uverbs_rereg_mr() jumps to put_new_uobj on a driver error\nwithout undoing the reassignment, so mr-\u003epd == new_pd while the usecnts\nstill charge the MR to orig_pd. ib_dereg_mr_user() then decrements\nnew_pd, whose count can reach zero while a memory window still references\nit; uverbs_free_pd() frees the PD on that count alone and rxe_mw_cleanup()\nwrites to freed memory:\n\n  BUG: KASAN: slab-use-after-free in __rxe_put+0x31/0xa0\n  Write of size 4 at addr ffff8881301dd690 by task rxe_poc/591\n   __rxe_put+0x31/0xa0\n   rxe_mw_cleanup+0x42/0x200\n   __rxe_cleanup+0x115/0x370\n   rxe_dealloc_mw+0x4c/0x80\n  Allocated by task 591:\n   ib_uverbs_alloc_pd+0x258/0x540\n  Freed by task 591:\n   ib_dealloc_pd_user+0x174/0x210\n   uverbs_free_pd+0x8d/0xc0\n   ib_uverbs_dealloc_pd+0x18e/0x1d0\n\nValidate the access flags before mutating any state so the callback either\napplies every requested change or none.","modified":"2026-10-08T02:52:58.477210272Z","published":"2026-10-06T08:46:51.638Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98366.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/08f12745cb72981aa2cabe214af0c7a42a856f0a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4dd7a53f1c5b44693c26dac4b9b5bd5bb9d604c8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7230cc456d4bb2221c20c5f1d22b38b8576aa16f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ae36a5b609ae79f4de966328b78d2584be9719a4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fe602c91a52e161ace4afd5bdb8f33270c554c6f"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98366.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98366"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c"},{"fixed":"08f12745cb72981aa2cabe214af0c7a42a856f0a"},{"fixed":"7230cc456d4bb2221c20c5f1d22b38b8576aa16f"},{"fixed":"fe602c91a52e161ace4afd5bdb8f33270c554c6f"},{"fixed":"4dd7a53f1c5b44693c26dac4b9b5bd5bb9d604c8"},{"fixed":"ae36a5b609ae79f4de966328b78d2584be9719a4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98366.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.5.0"},{"fixed":"6.6.158"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.112"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.54"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.8"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98366.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}