From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 1D028397922; Mon, 12 Oct 2026 16:48:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791823710; cv=none; b=ocQQL4JkwXRYwksfkyjMrLcFil9R6DRm/qPYdfcmkUesvuFhoXKzkHabto9GGTKqtRnzZn6OiOAGlvI5I1eK7syq/jRywIp/wYDAvC0gFS+2LLUom/M8Vf7eoovkTOGV8tRtzI41pn7CnNPo7jYIgRqzdHb4lrseR70V893EDlI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791823710; c=relaxed/simple; bh=mMH0te/tvNL90Fzjix9Jb5/yQwN4Tz8Lrk+WcISK7iE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=E/q5dghhTCS/KM94BgDQM15VWRXT8lSGLyzNckWgyWohThCkTsg/mQZOFw6M+K9p0CpNTYOfUWC1HaDua9RjIJExxvxTmDtZLjejmASCi7svDn1l8KsRaxxbpDVWDy/OKgUdLfK+9BcXTo7vvhsDNzzxiwXXn90OkarjASk1nns= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=L3Bv9WpI; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="L3Bv9WpI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 03C811F0089B; Mon, 12 Oct 2026 16:48:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791823708; bh=a5mP5nC8nPPlsIQNVn0JofAMSDeCWtdkqJAfFM+RFQ0=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=L3Bv9WpIFj/9+8iEAITVKPt4r5u7esiQ99zdQTN/X2zfuuFoP2dz6VzLMoqk3x9BQ GiLCQlJGaQxTJCrvXNxDmBAuMw3N+bY6qTDzPKdoYtI0gvsNqz5yvdUJsQyfkFyt81 S/rOIQdH2eICo1+xmN0VSiSQAbtq/cdHYvZQ7x8kT9A5nAv8HMAJXLIcMh/6gGv/gw 4EvSr6CyH6yHeHr4gAB7OMdimisJsFYFcRRPqYn0ov1k6kvSqO0rd8b+PEeOW7YyL5 Wv+O+KUKBFbNKjFZSWFPhH4ZavfUfUszcFlgm4HbAhj+hDRfLppJAjvauEz12Opvso 2rvU1oKXl6MNQ== Date: Mon, 12 Oct 2026 17:48:20 +0100 From: "Lorenzo Stoakes (ARM)" To: Helge Deller , Javier Martinez Canillas , Thomas Zimmermann , Bruno =?utf-8?Q?Pr=C3=A9mont?= , Jiri Kosina , Benjamin Tissoires , Bernie Thompson , Greg Kroah-Hartman , Steve Glendinning , Florian Tobias Schandinat Cc: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, Steve Glendinning , stable@vger.kernel.org Subject: Re: [PATCH 0/6] fbdev: fixup callers which ignore errors from fb_deferred_io_init() Message-ID: References: <20260926-fix-fbdefio-error-handling-v1-0-a94810b6e263@kernel.org> Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260926-fix-fbdefio-error-handling-v1-0-a94810b6e263@kernel.org> On Sat, Sep 26, 2026 at 02:16:58PM +0100, Lorenzo Stoakes (ARM) wrote: > Commit 56c134f7f1b5 ("fbdev: Track deferred-I/O pages in pageref struct") > converted fb_deferred_io_init() from a void function to one returning an > error value. > > However a number of callers don't seem to have been apprised of the fact > and continue to treat it like a void function. > > This is problematic, as upon allocation failure, struct > fb_info->fbdefio_state is NULL. > > That means when a subsequent operation is performed upon the driver, for > instance opening the file, a NULL pointer dereference occurs. > > Update all of the remaining drivers which fail to check this to do so. > > This issue was discovered as part of a separate series which updated logic > belonging to ssd1307fb. > > Also fix up a separate issue with a BUG_ON() occurring on allocation > failure for udlfb and smcufx. > > Signed-off-by: Lorenzo Stoakes (ARM) > --- > Lorenzo Stoakes (ARM) (6): > fbdev: ssd1307fb: check for fb_deferred_io_init() error > fbdev: xen-fbfront: check for fb_deferred_io_init() error > HID: picoLCD: check for fb_deferred_io_init() error > fbdev: udlfb: check for fb_deferred_io_init() error > fbdev: smscufx: check for fb_deferred_io_init() error > fbdev: sh_mobile_lcdc: check for fb_deferred_io_init() error Ping on this! I know timing is awful given a. the insane volume this cycle and b. LPC, but these are fairly mechanical things so should be relatively straightforward. > > drivers/hid/hid-picolcd_fb.c | 12 +++++++++--- > drivers/video/fbdev/sh_mobile_lcdcfb.c | 6 +++++- > drivers/video/fbdev/smscufx.c | 9 ++++++--- > drivers/video/fbdev/ssd1307fb.c | 6 +++++- > drivers/video/fbdev/udlfb.c | 9 ++++++--- > drivers/video/fbdev/xen-fbfront.c | 7 ++++++- > 6 files changed, 37 insertions(+), 12 deletions(-) > --- > base-commit: 6812ce4e4379ffc99c52401ec28f0d7ffbc36206 > change-id: 20260926-fix-fbdefio-error-handling-ab135b0193cb > > Best regards, > -- > Lorenzo Stoakes (ARM) > -- Cheers, Lorenzo