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Fri, 06 Mar 2026 03:26:02 -0800 (PST) From: Jens Axboe To: ming.lei@redhat.com, Mehul Rao Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org In-Reply-To: <20260305193146.304526-1-mehulrao@gmail.com> References: <20260305193146.304526-1-mehulrao@gmail.com> Subject: Re: [PATCH] ublk: fix NULL pointer dereference in ublk_ctrl_set_size() Message-Id: <177279636192.680057.1248751372115881016.b4-ty@kernel.dk> Date: Fri, 06 Mar 2026 04:26:01 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Mailer: b4 0.14.3 On Thu, 05 Mar 2026 14:31:46 -0500, Mehul Rao wrote: > ublk_ctrl_set_size() unconditionally dereferences ub->ub_disk via > set_capacity_and_notify() without checking if it is NULL. > > ub->ub_disk is NULL before UBLK_CMD_START_DEV completes (it is only > assigned in ublk_ctrl_start_dev()) and after UBLK_CMD_STOP_DEV runs > (ublk_detach_disk() sets it to NULL). Since the UBLK_CMD_UPDATE_SIZE > handler performs no state validation, a user can trigger a NULL pointer > dereference by sending UPDATE_SIZE to a device that has been added but > not yet started, or one that has been stopped. > > [...] Applied, thanks! [1/1] ublk: fix NULL pointer dereference in ublk_ctrl_set_size() commit: 25966fc097691e5c925ad080f64a2f19c5fd940a Best regards, -- Jens Axboe