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 86A1E2E11B9; Mon, 13 Apr 2026 16:27:49 +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=1776097669; cv=none; b=nNj9B8qNFCsw9R3zN0dLcTqxEcqpcibPIYyXKkS+BwU1cgSM5O0IDJM34OIs6+WtAWl8N+/eBpDw/fTUDvyBOrSbOPnhLxmoaBAaNMwpCIzHSoVpgDa2j5mw3qRZvMDdn1iFRXLtSPg4OLtq3lSGNFM0lXzbuJZm1FWaePsSjEg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776097669; c=relaxed/simple; bh=zA9g0ricYT1oDN/Z/dAvRcvDvJHtd+fRPx9DKLEHU+g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=c5Boe+lfOR1lmpyVAp0XjCDwf+ZUn1GcBde4uuZKO755q1IlT1IljiccaxIU7VqcocOjmygiKzCq7DSWVwVv6wzra+DJODSoCO8sjTO59Yhc6nFjuZA6Y4GuQ60dVyL0+/IQQOJJUJsymwIhbIZ76WiNrTPS4JKFDNyLlkUyEWM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=wj8MU5YJ; 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="wj8MU5YJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D35A3C2BCAF; Mon, 13 Apr 2026 16:27:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776097669; bh=zA9g0ricYT1oDN/Z/dAvRcvDvJHtd+fRPx9DKLEHU+g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wj8MU5YJu0AhvrCa7EULv3h7Xv5zwsytxmw87lSTa9k3D8Hs0NdSaP0LZr6O3ACqq 8hkZUiNwofS11GTxgU0bCoJHldiNjG5pADGwCrxy6XkXnazWHl7vEoqvgB5cmBAHiJ D8bwHTqc5oNkqhG5VDvS3M9ibopxoPInmyH/z0cw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jeongjun Park , Inki Dae Subject: [PATCH 5.15 225/570] drm/exynos: vidi: use ctx->lock to protect struct vidi_context member variables related to memory alloc/free Date: Mon, 13 Apr 2026 17:55:56 +0200 Message-ID: <20260413155838.883387639@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155830.386096114@linuxfoundation.org> References: <20260413155830.386096114@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-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 | 43 +++++++++++++++++++++++++------ 1 file changed, 35 insertions(+), 8 deletions(-) --- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c +++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c @@ -185,15 +185,17 @@ 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 (!ctx->raw_edid) ctx->raw_edid = (struct edid *)fake_edid_info; @@ -201,14 +203,21 @@ static ssize_t vidi_store_connection(str /* if raw_edid isn't same as fake data then it can't be tested. */ if (ctx->raw_edid != (struct edid *)fake_edid_info) { 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, @@ -243,11 +252,14 @@ 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) { struct edid *raw_edid; @@ -270,20 +282,27 @@ int vidi_connection_ioctl(struct drm_dev "failed to allocate raw_edid.\n"); return -ENOMEM; } + mutex_lock(&ctx->lock); ctx->raw_edid = raw_edid; + mutex_unlock(&ctx->lock); } else { /* * with connection = 0, free raw_edid * only if raw edid data isn't same as fake data. */ + mutex_lock(&ctx->lock); if (ctx->raw_edid && ctx->raw_edid != (struct edid *)fake_edid_info) { kfree(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; @@ -298,7 +317,7 @@ 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; } @@ -320,22 +339,24 @@ static int vidi_get_modes(struct drm_con struct vidi_context *ctx = ctx_from_connector(connector); struct edid *edid; int edid_len; - int count; + int count = 0; /* * the edid data comes from user side and it would be set * to ctx->raw_edid through specific ioctl. */ + + mutex_lock(&ctx->lock); if (!ctx->raw_edid) { DRM_DEV_DEBUG_KMS(ctx->dev, "raw_edid is null.\n"); - return 0; + goto fail; } edid_len = (1 + ctx->raw_edid->extensions) * EDID_LENGTH; edid = kmemdup(ctx->raw_edid, edid_len, GFP_KERNEL); if (!edid) { DRM_DEV_DEBUG_KMS(ctx->dev, "failed to allocate edid\n"); - return 0; + goto fail; } drm_connector_update_edid_property(connector, edid); @@ -344,6 +365,8 @@ static int vidi_get_modes(struct drm_con kfree(edid); +fail: + mutex_unlock(&ctx->lock); return count; } @@ -489,11 +512,15 @@ static int vidi_remove(struct platform_d { struct vidi_context *ctx = platform_get_drvdata(pdev); + mutex_lock(&ctx->lock); + if (ctx->raw_edid != (struct edid *)fake_edid_info) { kfree(ctx->raw_edid); ctx->raw_edid = NULL; } + mutex_unlock(&ctx->lock); + component_del(&pdev->dev, &vidi_component_ops); return 0;