From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792594328; b=hJbdBgmZIa8jv0ppX1NoQqDuYND1RWsW4AS6iLR9Yw4d5KM7BAyKkm7mhAuK7niCjNIx uXJTW3xIi56Akb0YFeOm27ZOhY9Hx9XvKHMWaFkWAWlZCHFRRwXus8o/kLydk73iJchD0 1YwLpbYzKaV3BOZVNyWI6JwV3Q0C3RBvRGBsAbVV3TR3kTxaFqL1k1oP7Qq/YI3PqmuNh shHyviCj9hk/re9GHnFPTlUkWnww7S/OljxP+2Jzc+CCCCvmtEkzmx8sB0fQfmZS510iE 5nI3jjiqwAO3UnJDQ+T4JviNsPpgVVwp0wOiVsM5KaItS2ZYP0FSMFfz+b8E29yEEyA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792594328; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=Im/ZP3l+PKCzpIj5lDtuXhlEt7fBzSnDEkajfy9FOp4=; b=TBTzga8WxtYnGug7New4nHNCfS0y3s6TKtzDo2IT50c/HdI97LYaBraCvAzSHxNcaevE Z1RCp09eRPTy/6iL/SQFpZIG77WRYsyo6N2S6TXuWKYiuszFDNYHns5ui73VEc/Z0Zzvt 4lGO032Oe2+wyUDcFiW86HSkWz6mhXUC4OgQnUoReG6yE32H6+GYTD/Vlpf+HELqqqFnZ DGtckIM2MUDXwKoB2a3+EjPMFfpGvCdIrDh1qn4FDmXn8diL8l7hvGzQ/COGmfmP1wG1K tMfMGyGp+aOvVESJ1vzwUsgmOvu9QBfu8siLsJ05lFE2rzmAx/UKnLImJCDK+Ods1AA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=f8IO7VnV; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1BD7D606A31A for ; Wed, 21 Oct 2026 14:52:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=f8IO7VnV Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F0D41F000C1; Wed, 21 Oct 2026 14:52:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792594328; bh=Im/ZP3l+PKCzpIj5lDtuXhlEt7fBzSnDEkajfy9FOp4=; h=Subject:To:Cc:From:Date; b=f8IO7VnVlzmw/gnN7T35ZLXch1ftnSze3fW4t8a/8e8YS4SwVyuwr7TZtmV1MDIhR pob1AOPRt0QmBHsNVBFCidGDCHGAvTKccywSD0Jj4XyvK6jrvLSQA5rQLS3kFsAbey GhqMzkf4CS48uEpcXFUN2P5/tM5Kj8fN6LEu4bPU= Subject: FAILED: patch "[PATCH] drm/i915/dmc: Harden DMC firmware payload parsing" failed to apply to 6.6-stable tree To: dibin.moolakadan.subrahmanian@intel.com,ankit.k.nautiyal@intel.com,joonas.lahtinen@linux.intel.com,mitulkumar.ajitkumar.golani@intel.com Cc: From: Date: Wed, 21 Oct 2026 16:47:11 +0200 Message-ID: <2026102111-doubling-vendetta-47d0@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 8bb1858db453cd4250e3b633f5d2d09206024ca6 # git commit -s git send-email --to '' --in-reply-to '2026102111-doubling-vendetta-47d0@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 8bb1858db453cd4250e3b633f5d2d09206024ca6 Mon Sep 17 00:00:00 2001 From: Dibin Moolakadan Subrahmanian Date: Tue, 22 Sep 2026 19:05:37 +0530 Subject: [PATCH] drm/i915/dmc: Harden DMC firmware payload parsing Validate the conversion of the DMC firmware size from dwords to bytes using check_mul_overflow() before calculating the firmware payload size. Reject zero-length payloads and zero MMIO counts in the DMC firmware header so malformed firmware is caught early. Also set dmc_fw_size only after the payload allocation succeeds. Fixes: eb805623d8b1 ("drm/i915/skl: Add support to load SKL CSR firmware.") Cc: stable@vger.kernel.org Assisted-by: Claude-Code:Sonnet-5 Signed-off-by: Dibin Moolakadan Subrahmanian Reviewed-by: Mitul Golani Signed-off-by: Ankit Nautiyal Link: https://patch.msgid.link/20260922133535.3180973-5-dibin.moolakadan.subrahmanian@intel.com (cherry picked from commit efde6601a1f1daedfe3dcc2816c934ddb44e3eef) Signed-off-by: Joonas Lahtinen diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c b/drivers/gpu/drm/i915/display/intel_dmc.c index a191eee240d9..725481012578 100644 --- a/drivers/gpu/drm/i915/display/intel_dmc.c +++ b/drivers/gpu/drm/i915/display/intel_dmc.c @@ -1120,7 +1120,7 @@ static u32 parse_dmc_fw_header(struct intel_dmc *dmc, } /* Cache the dmc header info. */ - if (mmio_count > mmio_count_max) { + if (!mmio_count || mmio_count > mmio_count_max) { drm_err(display->drm, "DMC firmware has wrong mmio count %u\n", mmio_count); return 0; } @@ -1166,13 +1166,21 @@ static u32 parse_dmc_fw_header(struct intel_dmc *dmc, disable_dmc_evt(display, dmc_id, dmc_info->mmioaddr[i], dmc_info->mmiodata[i]) ? " (disabling)" : ""); } - dmc_info->mmio_count = mmio_count; - dmc_info->start_mmioaddr = start_mmioaddr; rem_size -= header_len_bytes; /* fw_size is in dwords, so multiplied by 4 to convert into bytes. */ - payload_size = dmc_header->fw_size * 4; + if (check_mul_overflow(dmc_header->fw_size, 4u, &payload_size)) { + drm_err(display->drm, "DMC fw_size too large (%u dwords)\n", + dmc_header->fw_size); + return 0; + } + + if (!payload_size) { + drm_err(display->drm, "DMC firmware has empty payload\n"); + return 0; + } + if (rem_size < payload_size) goto error_truncated; @@ -1180,12 +1188,15 @@ static u32 parse_dmc_fw_header(struct intel_dmc *dmc, drm_err(display->drm, "DMC FW too big (%u bytes)\n", payload_size); return 0; } - dmc_info->dmc_fw_size = dmc_header->fw_size; dmc_info->payload = kmalloc(payload_size, GFP_KERNEL); if (!dmc_info->payload) return 0; + dmc_info->mmio_count = mmio_count; + dmc_info->start_mmioaddr = start_mmioaddr; + dmc_info->dmc_fw_size = dmc_header->fw_size; + payload = (u8 *)(dmc_header) + header_len_bytes; memcpy(dmc_info->payload, payload, payload_size);