CVE Catalog

CVE-2026-98366

Unknown
Published: Translated: NVD NIST

Summary

In the Linux kernel's RDMA/rxe subsystem, a vulnerability exists where rxe_rereg_user_mr() reassigns the PD pointer before validating access flags. If validation fails, the MR remains in an inconsistent state, leading to a use-after-free of the PD memory.

Risk Assessment

An attacker could exploit this to write to freed memory, potentially causing system integrity compromise, privilege escalation, or kernel panic. Systems using RDMA with the rxe implementation are affected.

Recommendation

Immediately update the Linux kernel to a version containing the fix that validates access flags before any state mutation. Monitor vendor security advisories for the patch.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: validate access flags before swapping the MR's PD rxe_rereg_user_mr() reassigns mr->ibmr.pd first and only then validates the IB_MR_REREG_ACCESS argument: if (flags & IB_MR_REREG_PD) { rxe_put(old_pd); rxe_get(pd); mr->ibmr.pd = ibpd; } if (flags & IB_MR_REREG_ACCESS) { if (access & ~RXE_ACCESS_SUPPORTED_MR) return ERR_PTR(-EOPNOTSUPP); mr->access = access; } Both flags pass the entry check because RXE_MR_REREG_SUPPORTED is IB_MR_REREG_PD | IB_MR_REREG_ACCESS, so a caller can reach the access check with mr->ibmr.pd already reassigned. mr->ibmr.pd is owned by the core, which adjusts pd->usecnt only on the success path: ib_uverbs_rereg_mr() jumps to put_new_uobj on a driver error without undoing the reassignment, so mr->pd == new_pd while the usecnts still charge the MR to orig_pd. ib_dereg_mr_user() then decrements new_pd, whose count can reach zero while a memory window still references it; uverbs_free_pd() frees the PD on that count alone and rxe_mw_cleanup() writes to freed memory: BUG: KASAN: slab-use-after-free in __rxe_put+0x31/0xa0 Write of size 4 at addr ffff8881301dd690 by task rxe_poc/591 __rxe_put+0x31/0xa0 rxe_mw_cleanup+0x42/0x200 __rxe_cleanup+0x115/0x370 rxe_dealloc_mw+0x4c/0x80 Allocated by task 591: ib_uverbs_alloc_pd+0x258/0x540 Freed by task 591: ib_dealloc_pd_user+0x174/0x210 uverbs_free_pd+0x8d/0xc0 ib_uverbs_dealloc_pd+0x18e/0x1d0 Validate the access flags before mutating any state so the callback either applies every requested change or none.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS