From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E54F0FD0049 for ; Sun, 1 Mar 2026 01:44:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=8f1FcX1dhFCAnb21Uy8sw7t5iaLztbBhswVlS1HDiF4=; b=LWZBI2OoRf9fqKmkEBc8EnxENo itPXyFAfYswnEjoILAvXDcX7n+y+j4+74pIPeNCX5ad1YPXhsIlX6MaTkR5l6LDW4kv4+BoXUB79q olkobom0fwe3hAzt0IKusDGzx/r7FsWI6u86fqQIjRnPWcaQkmtHz+IYmz3KqbtDAcPXxKtpn4Ftt vx4O8KhcuPVgeRUVxFJ2MI/iz4aYbZjg9blj+G5CWFEHtKq3GNwfLREE+3mPDSC6E/sWR3uN/TOWI Ycb+11BDB28G0GUFfhbdxkDpxdlIe9u6na2t2+ndEGmtfwAJ9rSFiVJdsk7Km/MMydO2MpujW4emh mLCq7EZQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vwVrS-0000000AdNz-3DJT; Sun, 01 Mar 2026 01:44:46 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vwVrP-0000000AdMq-1GEh for linux-arm-kernel@lists.infradead.org; Sun, 01 Mar 2026 01:44:44 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 08CB543C89; Sun, 1 Mar 2026 01:44:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3786CC19424; Sun, 1 Mar 2026 01:44:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772329482; bh=UL9K2W1kTjD0BBU0nfv/3OzUPNAlfrXIZhlnFgaUT5s=; h=From:To:Cc:Subject:Date:From; b=CfulXbdd68SzzaHljG4xb2cbQgp/vB1pZth5lxPXyvFVMykWps19N0FSySZApsc3I HeYa6pvUY84JNGyPuy3d3572p1EWNpLRPLDqRZv+VOnaslMrs4EjHS3Oe2RY+srrG4 QwXtbvTRyU2miGBmdpVDLLDeQmgpFyVaiFiuR0av05hZRIFHNtylT4L0I4QnXJZg0G 2vD+d4HDFYXWEAUv2r+p3QG+4XfKmosgFioFzXnF36V/TjfaB0vxvvhsVb0cKHC4r/ v+YtsQmInxqIZ4ClMXymJZX7POlr9kjZ+zor7AINyy5PQ4FjdXrYnA7EoLnrVPudBM LsgiN2mPzCxkg== From: Sasha Levin To: stable@vger.kernel.org, aha310510@gmail.com Cc: Inki Dae , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org Subject: FAILED: Patch "drm/exynos: vidi: use ctx->lock to protect struct vidi_context member variables related to memory alloc/free" failed to apply to 6.1-stable tree Date: Sat, 28 Feb 2026 20:44:40 -0500 Message-ID: <20260301014441.1707098-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 MIME-Version: 1.0 X-Patchwork-Hint: ignore X-stable: review Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260228_174443_375238_4A719DF9 X-CRM114-Status: GOOD ( 18.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The patch below does not apply to the 6.1-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 . Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 52b330799e2d6f825ae2bb74662ec1b10eb954bb Mon Sep 17 00:00:00 2001 From: Jeongjun Park Date: Mon, 19 Jan 2026 17:25:53 +0900 Subject: [PATCH] drm/exynos: vidi: use ctx->lock to protect struct vidi_context member variables related to memory alloc/free Exynos Virtual Display driver performs memory alloc/free operations without lock protection, which easily causes concurrency problem. For example, use-after-free can occur in race scenario like this: ``` CPU0 CPU1 CPU2 ---- ---- ---- vidi_connection_ioctl() if (vidi->connection) // true drm_edid = drm_edid_alloc(); // alloc drm_edid ... ctx->raw_edid = drm_edid; ... drm_mode_getconnector() drm_helper_probe_single_connector_modes() vidi_get_modes() if (ctx->raw_edid) // true drm_edid_dup(ctx->raw_edid); if (!drm_edid) // false ... vidi_connection_ioctl() if (vidi->connection) // false drm_edid_free(ctx->raw_edid); // free drm_edid ... drm_edid_alloc(drm_edid->edid) kmemdup(edid); // UAF!! ... ``` To prevent these vulns, at least in vidi_context, member variables related to memory alloc/free should be protected with ctx->lock. Cc: Signed-off-by: Jeongjun Park Signed-off-by: Inki Dae --- drivers/gpu/drm/exynos/exynos_drm_vidi.c | 38 ++++++++++++++++++++---- 1 file changed, 32 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/exynos/exynos_drm_vidi.c b/drivers/gpu/drm/exynos/exynos_drm_vidi.c index 9709c07e5d8f4..67bbf9b8bc0ef 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c +++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c @@ -187,29 +187,37 @@ static ssize_t vidi_store_connection(struct device *dev, const char *buf, size_t len) { struct vidi_context *ctx = dev_get_drvdata(dev); - int ret; + int ret, new_connected; - ret = kstrtoint(buf, 0, &ctx->connected); + ret = kstrtoint(buf, 0, &new_connected); if (ret) return ret; - - if (ctx->connected > 1) + if (new_connected > 1) return -EINVAL; + mutex_lock(&ctx->lock); + /* * Use fake edid data for test. If raw_edid is set then it can't be * tested. */ if (ctx->raw_edid) { DRM_DEV_DEBUG_KMS(dev, "edid data is not fake data.\n"); - return -EINVAL; + ret = -EINVAL; + goto fail; } + ctx->connected = new_connected; + mutex_unlock(&ctx->lock); + DRM_DEV_DEBUG_KMS(dev, "requested connection.\n"); drm_helper_hpd_irq_event(ctx->drm_dev); return len; +fail: + mutex_unlock(&ctx->lock); + return ret; } static DEVICE_ATTR(connection, 0644, vidi_show_connection, @@ -244,11 +252,14 @@ int vidi_connection_ioctl(struct drm_device *drm_dev, void *data, return -EINVAL; } + mutex_lock(&ctx->lock); if (ctx->connected == vidi->connection) { + mutex_unlock(&ctx->lock); DRM_DEV_DEBUG_KMS(ctx->dev, "same connection request.\n"); return -EINVAL; } + mutex_unlock(&ctx->lock); if (vidi->connection) { const struct drm_edid *drm_edid; @@ -282,14 +293,21 @@ int vidi_connection_ioctl(struct drm_device *drm_dev, void *data, "edid data is invalid.\n"); return -EINVAL; } + mutex_lock(&ctx->lock); ctx->raw_edid = drm_edid; + mutex_unlock(&ctx->lock); } else { /* with connection = 0, free raw_edid */ + mutex_lock(&ctx->lock); drm_edid_free(ctx->raw_edid); ctx->raw_edid = NULL; + mutex_unlock(&ctx->lock); } + mutex_lock(&ctx->lock); ctx->connected = vidi->connection; + mutex_unlock(&ctx->lock); + drm_helper_hpd_irq_event(ctx->drm_dev); return 0; @@ -304,7 +322,7 @@ static enum drm_connector_status vidi_detect(struct drm_connector *connector, * connection request would come from user side * to do hotplug through specific ioctl. */ - return ctx->connected ? connector_status_connected : + return READ_ONCE(ctx->connected) ? connector_status_connected : connector_status_disconnected; } @@ -327,11 +345,15 @@ static int vidi_get_modes(struct drm_connector *connector) const struct drm_edid *drm_edid; int count; + mutex_lock(&ctx->lock); + if (ctx->raw_edid) drm_edid = drm_edid_dup(ctx->raw_edid); else drm_edid = drm_edid_alloc(fake_edid_info, sizeof(fake_edid_info)); + mutex_unlock(&ctx->lock); + drm_edid_connector_update(connector, drm_edid); count = drm_edid_connector_add_modes(connector); @@ -483,9 +505,13 @@ static void vidi_remove(struct platform_device *pdev) { struct vidi_context *ctx = platform_get_drvdata(pdev); + mutex_lock(&ctx->lock); + drm_edid_free(ctx->raw_edid); ctx->raw_edid = NULL; + mutex_unlock(&ctx->lock); + component_del(&pdev->dev, &vidi_component_ops); } -- 2.51.0