From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-106113.protonmail.ch (mail-106113.protonmail.ch [79.135.106.113]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 71314446070 for ; Tue, 18 Aug 2026 09:53:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=79.135.106.113 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787046822; cv=none; b=QxLU4o6ZcR14qg/Ni8TGLHPEEupIUuCA0vwAxmvxCS44Lum09nm04XJHRhNqHysDxaqJHVkBTTA9FtGEKIvJ2mGGxZRRYA4wEu7zOqaGHQYPgSyQQeVGZaz62a8NRf3HWYO4NvupmlcWYm0N3pnfWhtL55iV3E4wbsNOCZrDj58= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787046822; c=relaxed/simple; bh=9luHGON2wvOVH0eHgE8BxiZ+qOB4Tg/p6Fe76BNvPmA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=oiY6NA11oJGdTuZHTG2QJ80YfB1VPdfEf+vWiYKOVnHbHfx+Of4WhrVr1WgjDyk7yJV69AhJXa3OJfB028svkr2cK4slOklt4sNP6D64/jRszk5fXrSm924mcACfjvE6co4gmcESW1OGw1U9A+hIUv/wHdz3Y2rCdKXeyGJN/Ss= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=runtimeverification.com; spf=pass smtp.mailfrom=runtimeverification.com; dkim=pass (2048-bit key) header.d=runtimeverification.com header.i=@runtimeverification.com header.b=b5YDbcbH; arc=none smtp.client-ip=79.135.106.113 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=runtimeverification.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=runtimeverification.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=runtimeverification.com header.i=@runtimeverification.com header.b="b5YDbcbH" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=runtimeverification.com; s=protonmail; t=1787046818; x=1787306018; bh=9luHGON2wvOVH0eHgE8BxiZ+qOB4Tg/p6Fe76BNvPmA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References:From:To: Cc:Date:Subject:Reply-To:Feedback-ID:Message-ID:BIMI-Selector; b=b5YDbcbHTsBr93QKneFIDNQS0xOaNjDepRxoNhc+B6/1HYW4H0e/bjgoYHNuYVMAJ tzMxQK8xCknoRQX/Butrcof8T+I4vYS/7J8tWqjKJLEDEH5KRd1K8MFoBnmozkC2qt DeFJwTkd0uh+8G4nRPfyQhs7z2HOPhMi6o9Hp66y48d4gK2jqwIHRmxHHdbssXZNVn SnZvXjc02rCTtD8GjYi0Sg1lrk45CxGkfzlC1iDdv08UJJhw/C/59v0CP7rYhQh9G9 OGLBSWYbm5EDz2Z1sX0iRdJ35oWCMBsZiLqoCg/MIquUx3cItgfepgr6Xae34Id9fA 9hKF39wOZgGHg== X-Pm-Submission-Id: 4hPQ4t61Qcz1DF6r From: Natasha Klaus To: ribalda@chromium.org, noambs2999@gmail.com Cc: laurent.pinchart@ideasonboard.com, hansg@kernel.org, mchehab@kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] media: uvcvideo: Skip frame descriptors with a zero computed size Date: Tue, 18 Aug 2026 12:53:27 +0300 Message-Id: <20260818095327.372080-1-natalie.klaus@runtimeverification.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260818094010.353021-1-natalie.klaus@runtimeverification.com> References: <20260818094010.353021-1-natalie.klaus@runtimeverification.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Three more things on the refactor, from reading it rather than running it. Placement: bufsize is declared at uvc_driver.c:300 and the block closes at 327, while interval parsing runs 329-354, so at the proposed position the variable is out of scope. And the exemption a check outside the branch would need is format->flags & UVC_FMT_FLAG_COMPRESSED, which is the branch condition at line 299 itself. The compressed case is worse than frame based alone. For UVC 1.10 and later uvc_fixup_video_ctrl() at uvc_video.c:214-218 never consumes the descriptor value, the size comes from the probe response. An MJPEG descriptor reporting zero is inert on those devices today, so a check outside the branch would skip those frames and break cameras that stream fine. -ENODATA already appears in this driver with the opposite polarity, at uvc_video.c:1284 and :1310, where it means drop this payload and carry on. Using it for the fatal case reads backwards against that. The mechanical parts of your refactor hold: buffer[0] cannot be zero because the USB core truncates the config at the first bLength < 2 descriptor (config.c:706, :785), the interval array is pre-counted at uvc_driver.c:718-729 with *intervals += n after every skip return, and all frames[] access is positional. Not tested on hardware. I will build and test before sending the series. Natasha