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 8AE831396CA; Mon, 18 Dec 2023 12:47:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mTDCqneM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 33377C433C7; Mon, 18 Dec 2023 12:47:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702903639; bh=bsY4LoZN8yFf7ZKDhtOZtbxzVI3SP6Zj2i2bqOJr2zw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mTDCqneMkN0FGraV5u8ArwYSyU5wM9A9iUW98tudZNqKptK9k6iY+zg2ZxnmQffoZ 3mCiIiwgRdqq8ofVf9TEbyADxZsGEAf56XBYBa9AhBwQBnImWV+eIEuB9994oM/mXF xMADmB0w8pgYJbkCbGHNVK1Rj5B+sO3VJ/+mHtVRLWwHef16JZZBX/V6mVwAYnSubp 6706TPEF55zzOa3bP6QcCsxIzfTgw7n2z26tcriN0imNAjgbKA8gnjYXKOR5Em/ed4 z8/sen3cjYHUSul0xeOvrLyy1xwVNX87I+SytMnmhG9HUPrcKS5u8h0luq8eM+Pmx6 ojNkhmy+YmnUQ== 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 4.19 3/6] drm/crtc: Fix uninit-value bug in drm_mode_setcrtc Date: Mon, 18 Dec 2023 07:47:08 -0500 Message-ID: <20231218124713.1382373-3-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231218124713.1382373-1-sashal@kernel.org> References: <20231218124713.1382373-1-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 4.19.302 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 6e241a3c31ee3..52a1bfeef0d9c 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -573,8 +573,7 @@ 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 -EINVAL; @@ -719,6 +718,7 @@ 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; @@ -739,6 +739,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, connector->name); connector_set[i] = connector; + num_connectors++; } } @@ -747,7 +748,7 @@ 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)) @@ -760,7 +761,7 @@ 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