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 A13725754F; Mon, 18 Dec 2023 12:45:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MkHd+m4l" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1917BC433C8; Mon, 18 Dec 2023 12:45:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702903522; bh=2iwNU4oThQUd0yeP7a35z2BoHThYhHlJhvnTtyhpVTQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MkHd+m4l9nJBRAgcvvUkjWA1MbPRdJu6p84w8Vgm88uxdLjF7U79lDnN4VObI0jiO bVJz+lvNu4qvjQMfiMv4WvqJ0URRUCGo7qBPZoLmgn1rczr+XbhL+yqHlgC4WXfoGu sa0A0gh5DA4vb4U8/TnDc+rIEh0n7GzSQyTctV8ctBja4fXucisp4XsvJBkWIpIc9G eqCOmfRZfwRPxXQaXErKbuno5AdXT7wSkJZGTSwT8CouRjEPzrQO3iTQjtXv+iCjmu cUvW88u8hVAJFZxk4VR0kq/9d4tZaita8PWZuip2guylQOBCIQ4dRtauzP9B0PcPNz vO5TfQSar289g== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ziqi Zhao , syzbot+4fad2e57beb6397ab2fc@syzkaller.appspotmail.com, Harshit Mogalapalli , Maxime Ripard , Sasha Levin , maarten.lankhorst@linux.intel.com, tzimmermann@suse.de, airlied@gmail.com, daniel@ffwll.ch, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 6.1 05/15] drm/crtc: Fix uninit-value bug in drm_mode_setcrtc Date: Mon, 18 Dec 2023 07:44:52 -0500 Message-ID: <20231218124513.1380056-5-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231218124513.1380056-1-sashal@kernel.org> References: <20231218124513.1380056-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.1.68 Content-Transfer-Encoding: 8bit From: Ziqi Zhao [ Upstream commit 3823119b9c2b5f9e9b760336f75bc989b805cde6 ] The connector_set contains uninitialized values when allocated with kmalloc_array. However, in the "out" branch, the logic assumes that any element in connector_set would be equal to NULL if failed to initialize, which causes the bug reported by Syzbot. The fix is to use an extra variable to keep track of how many connectors are initialized indeed, and use that variable to decrease any refcounts in the "out" branch. Reported-by: syzbot+4fad2e57beb6397ab2fc@syzkaller.appspotmail.com Signed-off-by: Ziqi Zhao Reported-and-tested-by: syzbot+4fad2e57beb6397ab2fc@syzkaller.appspotmail.com Tested-by: Harshit Mogalapalli Link: https://lore.kernel.org/r/20230721161446.8602-1-astrajoan@yahoo.com Signed-off-by: Maxime Ripard Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_crtc.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index df9bf3c9206e7..d718c17ab1e9f 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -715,8 +715,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, struct drm_mode_set set; uint32_t __user *set_connectors_ptr; struct drm_modeset_acquire_ctx ctx; - int ret; - int i; + int ret, i, num_connectors; if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EOPNOTSUPP; @@ -851,6 +850,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, goto out; } + num_connectors = 0; for (i = 0; i < crtc_req->count_connectors; i++) { connector_set[i] = NULL; set_connectors_ptr = (uint32_t __user *)(unsigned long)crtc_req->set_connectors_ptr; @@ -871,6 +871,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, connector->name); connector_set[i] = connector; + num_connectors++; } } @@ -879,7 +880,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, set.y = crtc_req->y; set.mode = mode; set.connectors = connector_set; - set.num_connectors = crtc_req->count_connectors; + set.num_connectors = num_connectors; set.fb = fb; if (drm_drv_uses_atomic_modeset(dev)) @@ -892,7 +893,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, drm_framebuffer_put(fb); if (connector_set) { - for (i = 0; i < crtc_req->count_connectors; i++) { + for (i = 0; i < num_connectors; i++) { if (connector_set[i]) drm_connector_put(connector_set[i]); } -- 2.43.0