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[79.57.139.67]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49b4e2c1af7sm67145705e9.15.2026.08.27.10.18.18 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Aug 2026 10:18:19 -0700 (PDT) From: Norbert Szetei Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3826.700.81.1.4\)) Subject: [PATCH] RDMA/rxe: validate access flags before swapping the MR's PD Message-Id: <46E1D5C0-24BE-4D01-BDB3-634FE09B22C5@doyensec.com> Date: Thu, 27 Aug 2026 19:18:07 +0200 Cc: Zhu Yanjun , Jason Gunthorpe , Leon Romanovsky , linux-kernel@vger.kernel.org To: linux-rdma@vger.kernel.org X-Mailer: Apple Mail (2.3826.700.81.1.4) Content-Type: text/plain; charset="utf-8" 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 =3D ibpd; } if (flags & IB_MR_REREG_ACCESS) { if (access & ~RXE_ACCESS_SUPPORTED_MR) return ERR_PTR(-EOPNOTSUPP); mr->access =3D 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 =3D=3D 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. Fixes: 544c7f62cf32 ("RDMA/rxe: Implement rereg_user_mr") Cc: stable@vger.kernel.org Signed-off-by: Norbert Szetei Reviewed-by: Zhu Yanjun --- drivers/infiniband/sw/rxe/rxe_verbs.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/= rxe/rxe_verbs.c index 96c7716057fe..3864284522eb 100644 --- a/drivers/infiniband/sw/rxe/rxe_verbs.c +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c @@ -1331,19 +1331,20 @@ static struct ib_mr *rxe_rereg_user_mr(struct ib_mr= *ibmr, int flags, if (err) return ERR_PTR(err); =20 + if ((flags & IB_MR_REREG_ACCESS) && + (access & ~RXE_ACCESS_SUPPORTED_MR)) { + rxe_err_mr(mr, "access =3D %#x not supported\n", access); + return ERR_PTR(-EOPNOTSUPP); + } + if (flags & IB_MR_REREG_PD) { rxe_put(old_pd); rxe_get(pd); mr->ibmr.pd =3D ibpd; } =20 - if (flags & IB_MR_REREG_ACCESS) { - if (access & ~RXE_ACCESS_SUPPORTED_MR) { - rxe_err_mr(mr, "access =3D %#x not supported\n", access); - return ERR_PTR(-EOPNOTSUPP); - } + if (flags & IB_MR_REREG_ACCESS) mr->access =3D access; - } =20 return NULL; } --=20 2.55.0