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 06EDBFD0048 for ; Sun, 1 Mar 2026 01:25:11 +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=ZUczDqKtC0Zyy7nZ00UE4npkX2l8TrrHJwv+R4Mng1A=; b=ckXrhVnYkoWSkxDiRbE1z8+FzG JUFw+Y7KkLFEAjBEqEXt1kadGEc/lLeZ5uR3wArmx/jTHmeNZMsyEjitLDoKQzRFFF8UCsKCm6rLg KPQMXFKueAC4ObSnONOUgyMTlxtsKcM7Y2sIBtjIlYMlzl7sG7xqDMjb+KwVgr42/PFaR7PPP+ZFN vacND0TuKq9UAR+ylQH701SlXDMawCEe24R5Ust3g4BSyS+dNJidlik4K/H1rxtV2CUpOAkthPHqx d9tRuN2mSyVKmO+/T1CYzEndCVRQNAb8xmqFK8nrDLoLUGeC7EAyys49tqrcIP9obk/02T6DS2kbk HKQq3f2w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vwVYP-0000000AVyy-2CRp; Sun, 01 Mar 2026 01:25:05 +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 1vwVYK-0000000AVw8-3edJ for linux-arm-kernel@lists.infradead.org; Sun, 01 Mar 2026 01:25:04 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 934604022A; Sun, 1 Mar 2026 01:25:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA830C19424; Sun, 1 Mar 2026 01:24:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772328300; bh=rRSh1/DAJbQXSr7bDILUoxZnB5otAxKreUpqr3iT4sk=; h=From:To:Cc:Subject:Date:From; b=ShJeIHwZ02tlTFp0aXaO9X1KvSQ7xsZ1RtDUIka4/iJxq56i+4TF7w089/P0kg4b1 1GDYIFAVDowR71OXt8+MzRyqQxXfHSTJrsL3IDy/xQJd8ixrMoeHr228SkMY7yXSr8 81GXNPvPTJN0jz1A/0/9xkXR8nw2qBq4TwUPVJMJLOA6rAxeDdLQsie+lmhFvDixBB 4Bti7MhP18QU2F+aZlOCMi0kY7mCOFbtPvK3gJBEaqyJ9Lp6Mb/bbdENvCYJU3pJKV iP23tUqYXLWHxTmAmQeiGahDhSpWZjmFIpRJNLaotQe3NQvVaw3PR2DOE2fMF69tE9 nLZICA3CAqmYg== 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 6.12-stable tree Date: Sat, 28 Feb 2026 20:24:58 -0500 Message-ID: <20260301012458.1681957-1-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_172503_111948_553CC711 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 6.12-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