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Thu, 12 Nov 2026 07:49:37 -0800 (PST) Received: from stjepan-Aspire-F5-573G.tailc0f20e.ts.net ([2a00:1bb8:118:d39e:4868:f22e:b51d:7cb]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4bb4e2538b9sm139337155e9.1.2026.11.12.07.49.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Nov 2026 07:49:37 -0800 (PST) From: Stjepan Poljak To: "Michael S. Tsirkin" , Jason Wang Cc: Francesco Valla , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Xuan Zhuo , Andy Lutomirski , Bjorn Andersson , Mathieu Poirier , virtualization@lists.linux.dev, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/2] virtio_ring: reject a split ring size that is not a power of two again Date: Thu, 12 Nov 2026 16:49:16 +0100 Message-ID: <20261112154927.4004184-2-stjepan.poljak@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261112154927.4004184-1-stjepan.poljak@gmail.com> References: <20261112154927.4004184-1-stjepan.poljak@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The split ring indexes its avail and used rings with num - 1 as a mask, so its size must be a power of two. Commit 2a2d1382fe9d ("virtio: Add improved queue allocation API") moved that check from vring_new_virtqueue() into the new allocation path, which vring_new_virtqueue() does not use. remoteproc calls vring_new_virtqueue() with a ring size from the firmware, checked only to be non-zero. With 100 entries, for example, the driver would put buffers 4 and 8 in avail slot 0. The device would look for them at slots 4 and 8, possibly reading the wrong data. Put the check back for the split ring; the packed ring has no such restriction. Fixes: 2a2d1382fe9d ("virtio: Add improved queue allocation API") Signed-off-by: Stjepan Poljak --- remoteproc still reports this as -ENOMEM, although the "Bad virtqueue length" error names the cause. Returning an error pointer from vring_new_virtqueue() is left for later; the same change for vring_create_virtqueue() is here: https://lore.kernel.org/r/20261106055635.3019889-1-stjepan.poljak@gmail.com v2: - Log with dev_err() rather than dev_warn(), and say in the message why the length is bad (Francesco) --- drivers/virtio/virtio_ring.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index f683a2d6a200..f855b8d41575 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -3513,6 +3513,13 @@ struct virtqueue *vring_new_virtqueue(unsigned int index, name, map); } + /* The split ring indexes its rings with num - 1 as a mask. */ + if (!is_power_of_2(num)) { + dev_err(&vdev->dev, + "Bad virtqueue length %u (not a power of two)\n", num); + return NULL; + } + vring_init(&vring_split.vring, num, pages, vring_align); return __vring_new_virtqueue_split(index, &vring_split, vdev, weak_barriers, context, notify, callback, name, -- 2.53.0