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Thu, 11 Jun 2026 10:29:10 -0700 (PDT) Received: from localhost.localdomain ([62.77.90.70]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4606c0c9c00sm440421f8f.12.2026.06.11.10.29.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Jun 2026 10:29:09 -0700 (PDT) Date: Thu, 11 Jun 2026 19:29:08 +0200 From: Michal =?utf-8?Q?Koutn=C3=BD?= To: Ren Wei Cc: cgroups@vger.kernel.org, tj@kernel.org, hannes@cmpxchg.org, pandit.parav@gmail.com, yuantan098@gmail.com, zcliangcn@gmail.com, bird@lzu.edu.cn, tr0jan@lzu.edu.cn, d4n.for.sec@gmail.com Subject: Re: [PATCH 1/1] cgroup: rdma: free idle pools during cgroup teardown Message-ID: References: <9eb365a37ab83f38686007f8a61a656759d39bd7.1781092143.git.d4n.for.sec@gmail.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="fm5vjrnfdbne7u5j" Content-Disposition: inline In-Reply-To: <9eb365a37ab83f38686007f8a61a656759d39bd7.1781092143.git.d4n.for.sec@gmail.com> --fm5vjrnfdbne7u5j Content-Type: text/plain; protected-headers=v1; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH 1/1] cgroup: rdma: free idle pools during cgroup teardown MIME-Version: 1.0 On Thu, Jun 11, 2026 at 02:13:16AM +0800, Ren Wei wrote: > From: Daming Li >=20 > rdmacg_css_offline() converts each pool to all-max limits so the > existing reclaim path can free it after the last uncharge. However, > zero-usage pools are already reclaimable at that point and leaving them > linked until rdmacg_css_free() lets later device teardown hit a > use-after-free when free_cg_rpool_locked() deletes cg_node from a freed > cgroup list head. That's a valid problem and good analysis. The rpool->cg_node points to rdma_cgroup w/out bumping a refcount on respective css hence the observed UaF. > Free zero-usage pools directly from rdmacg_css_offline() while holding > rdmacg_mutex. This keeps the existing reclaim rule, avoids new lifetime > states, and ensures a cgroup cannot be freed with reclaimable rdmacg > pools still attached. I see this approach works (without explicit ref bump and complications arising from that tracking). The shortened availability of events/peak should be OK as those are meant to be only for onlined cgs. >=20 > Fixes: 39d3e7584a68 ("rdmacg: Added rdma cgroup controller") > Cc: stable@vger.kernel.org > Reported-by: Yuan Tan > Reported-by: Zhengchuan Liang > Reported-by: Xin Liu > Assisted-by: Codex:GPT-5.4 > Co-developed-by: Luxing Yin > Signed-off-by: Luxing Yin > Signed-off-by: Daming Li > Signed-off-by: Ren Wei > --- > kernel/cgroup/rdma.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) Reviewed-by: Michal Koutn=FD --fm5vjrnfdbne7u5j Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iJEEABYKADkWIQRCE24Fn/AcRjnLivR+PQLnlNv4CAUCairwYBsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMiwyLDIACgkQfj0C55Tb+AgBxQEA2rVEVlZsIW9V0G2vfZZR vD1MlvtgdovVj6cOHe/3ML4A/0a1UW+YdRe6BaYYPMHh5cHho0xbeQnEbMU2V4pb s2wK =7hlL -----END PGP SIGNATURE----- --fm5vjrnfdbne7u5j--