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 5CA5D17BB2A; Wed, 25 Sep 2024 11:42:17 +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=1727264539; cv=none; b=nVqo2/V4QCICmSWyvsTTH63/tuajgm6QBao8wdZDAhkmKy0qH89STJyYVMfuyrwQCu/TsbJ5YuAnCjB3UwAqnKZ9oF3NcsggJr80M3WgeOWg3yvJNkYy0OF47wCe7YuqR7/aNNR5+U1Imoz7TzJGsauzhMIiSLoNW0Y8JfADP/Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727264539; c=relaxed/simple; bh=jHudm0CECuKh1KiFB3Pzw6IIjb7GizByG8fAtQfyH6U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SDx7MXyVwPmV8uycQjEXuE1+cpp2/UPzopMUDiUDMxNoK130GXtjwwrrm7sVStiT6dPWYWUwMeiOrsCWgl5N2wtcs5or2Z4SkS7oVrjjkXQ3QudtzZizHL8fA+U1w/4dl+r0sjQSRWSvbXuSmhsEXUOq1Vf4hDm3E373Rp5BY8E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lFnxtXE2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lFnxtXE2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 44300C4CECD; Wed, 25 Sep 2024 11:42:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727264537; bh=jHudm0CECuKh1KiFB3Pzw6IIjb7GizByG8fAtQfyH6U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lFnxtXE2C3ne3woi2mgIUaRUH9UHGtZqjym4zKxgSEHHZoFip05cWDaiLC3MoiE5e hbluYByaKBsSjgKvidMk5/i5i8dJnuJGZ2mkT76NoPGW0Tf+vGi4fhOQ6k1FXNNqgt NxOR258WzFc+XKLiiHvs2E07voR7KDVojdZRD0HQkhcXwXjVz29k6kDMkxAyHnByHo irnF/n/KCCW847IkayQWFWFMFgJmVzTkwXneoh9PxuXNoxSGrpr4vvWl8NYXdKyPy3 x/Yax5y928VcZhTCTKTlTSBBEJ1DtLOR44fip/LQK0msn86y18XkSFfd6dyQPZ3oao 3vXoMEphavwLw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kaixin Wang , Helge Deller , Sasha Levin , laurent.pinchart@ideasonboard.com, kuninori.morimoto.gx@renesas.com, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 6.11 115/244] fbdev: pxafb: Fix possible use after free in pxafb_task() Date: Wed, 25 Sep 2024 07:25:36 -0400 Message-ID: <20240925113641.1297102-115-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240925113641.1297102-1-sashal@kernel.org> References: <20240925113641.1297102-1-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 6.11 Content-Transfer-Encoding: 8bit From: Kaixin Wang [ Upstream commit 4a6921095eb04a900e0000da83d9475eb958e61e ] In the pxafb_probe function, it calls the pxafb_init_fbinfo function, after which &fbi->task is associated with pxafb_task. Moreover, within this pxafb_init_fbinfo function, the pxafb_blank function within the &pxafb_ops struct is capable of scheduling work. If we remove the module which will call pxafb_remove to make cleanup, it will call unregister_framebuffer function which can call do_unregister_framebuffer to free fbi->fb through put_fb_info(fb_info), while the work mentioned above will be used. The sequence of operations that may lead to a UAF bug is as follows: CPU0 CPU1 | pxafb_task pxafb_remove | unregister_framebuffer(info) | do_unregister_framebuffer(fb_info) | put_fb_info(fb_info) | // free fbi->fb | set_ctrlr_state(fbi, state) | __pxafb_lcd_power(fbi, 0) | fbi->lcd_power(on, &fbi->fb.var) | //use fbi->fb Fix it by ensuring that the work is canceled before proceeding with the cleanup in pxafb_remove. Note that only root user can remove the driver at runtime. Signed-off-by: Kaixin Wang Signed-off-by: Helge Deller Signed-off-by: Sasha Levin --- drivers/video/fbdev/pxafb.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/video/fbdev/pxafb.c b/drivers/video/fbdev/pxafb.c index 2ef56fa28aff3..5ce02495cda63 100644 --- a/drivers/video/fbdev/pxafb.c +++ b/drivers/video/fbdev/pxafb.c @@ -2403,6 +2403,7 @@ static void pxafb_remove(struct platform_device *dev) info = &fbi->fb; pxafb_overlay_exit(fbi); + cancel_work_sync(&fbi->task); unregister_framebuffer(info); pxafb_disable_controller(fbi); -- 2.43.0