From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7AF2954723; Fri, 13 Feb 2026 13:54:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770990857; cv=none; b=SwoFMFVfH/gWITVFr7tWNa1+e7A3UD1DLo24bvhBRfLS5HcTY/r7gt4/OqcciQaaaEJhYrTHo80nZ+Y8cktGgPVw7wSc3nQ+g1uLzJ+s7/2PSnDqWPNvMJ8OVhOpIR08de0PYJIIuIyzY6HYmFs0VEJ/RiC6dm8YWvz/zY3cvUU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770990857; c=relaxed/simple; bh=bjTNacvYP4wzmx5fe1sSlvF2fX0NAeWZcEVC7Z+a8mY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PI9QnBzUxWfYgWrNtQt2Ia9/ruDnI+LLbfZ5YfthDIi0z0A0TTswIYGJ4E2RbuM12hkCCtV9vF6X6Q0zVTOphVQkXKt3g+vBGvBrX4LVsIQWxc4rcKSHbtwTr436jkosIhLZRY/jWrAEh/xoRkTSFXhaKV3+b7YcPtz/WOTfBqY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CbO8D/Fm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CbO8D/Fm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06170C116C6; Fri, 13 Feb 2026 13:54:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1770990857; bh=bjTNacvYP4wzmx5fe1sSlvF2fX0NAeWZcEVC7Z+a8mY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CbO8D/Fm6lk42jHarHdVpi4pPti7skzXBgMNl7IdkjCS7rYhvpT+2FJNNkq53k7pq YWSYChj7UA0PXXxNp8LBQgBIXgjFsYG3+VinYYpHEO0VBMdEh1erhHXoIXGKJ57jKu /LeLCtxHceqsl7TL+w4P0QlBTPwq9XrMFGD5AQrA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jeongjun Park , Inki Dae Subject: [PATCH 6.18 46/49] drm/exynos: vidi: use ctx->lock to protect struct vidi_context member variables related to memory alloc/free Date: Fri, 13 Feb 2026 14:48:30 +0100 Message-ID: <20260213134710.547802422@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260213134708.885500854@linuxfoundation.org> References: <20260213134708.885500854@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeongjun Park commit 52b330799e2d6f825ae2bb74662ec1b10eb954bb upstream. 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 Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/exynos/exynos_drm_vidi.c | 38 ++++++++++++++++++++++++++----- 1 file changed, 32 insertions(+), 6 deletions(-) --- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c +++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c @@ -186,29 +186,37 @@ static ssize_t vidi_store_connection(str 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, @@ -238,11 +246,14 @@ int vidi_connection_ioctl(struct drm_dev 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; @@ -262,14 +273,21 @@ int vidi_connection_ioctl(struct drm_dev "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; @@ -284,7 +302,7 @@ static enum drm_connector_status vidi_de * 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; } @@ -307,11 +325,15 @@ static int vidi_get_modes(struct drm_con 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); @@ -456,9 +478,13 @@ static void vidi_remove(struct platform_ { 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); }