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 DD49E3D6F1F for ; Thu, 8 Jan 2026 13:23:15 +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=1767878597; cv=none; b=cqRhfvNxksrOI6YqHdMvnEbEecGZduajiCQ7o3x9DOQBgdmlebTVTES2cf/tMpCHnM6dP4lohoO+mW1FD0NTn5hctRNDoMZ6NOXxqvu2KHSV/SfNZfDVX3c+HbAQcSTm206dp8uALyHogu1Nvb8TfwwaxnLC4NIJc6lA5pxuvX4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767878597; c=relaxed/simple; bh=0VVniBlVCpxELfrqm260TmcO8/C54jNjx76bmADaXbM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JDz2cdBc6GSUvKaqLYfjzOPASFDWsA0CeXREGvdrjovakRFQ6F0acOdmWeqzSSqRqanuIFNF5Q4tuOD8tD/rCCB6SOi53gReJDnruavVM4LaJQb20PQ+JdIsZ8HzZPORkGEBxXFZfMz2UMadJ7HzOKLH2jdbeqld/EFpoml0yS0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=MTbavVW2; 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="MTbavVW2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E44BEC16AAE; Thu, 8 Jan 2026 13:23:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767878595; bh=0VVniBlVCpxELfrqm260TmcO8/C54jNjx76bmADaXbM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MTbavVW20xnV68QxOYyEZeePV1E6OZub7Wf2YzL0drdqApjMX+boz7H7Wiqw2Xc/Q DptBmvtLuwqDPHWtcnq1vzoNKcSgArYSx6x6KDCvLFTmqzyAfPxIW6ZsFd+hi2jBNn YJPO9c+TggokLhmUUSmN/y1+OHjnVzRWJDivOP7w= Date: Thu, 8 Jan 2026 14:23:12 +0100 From: Greg Kroah-Hartman To: Ben Hutchings Cc: Sasha Levin , Thorsten Glaser , Helge Deller , Junjie Cao , Gianluca Renzi , =?iso-8859-1?Q?Camale=F3n?= , William Burrow , 1123750@bugs.debian.org, Salvatore Bonaccorso , stable Subject: Re: [5.10] regression: virtual consoles 2-12 unusable Message-ID: <2026010803-gem-puzzle-640d@gregkh> References: <176626831842.2137.9290349746475307418.reportbug@x61p.mirbsd.org> <176626831842.2137.9290349746475307418.reportbug@x61p.mirbsd.org> Precedence: bulk X-Mailing-List: stable@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: On Fri, Jan 02, 2026 at 05:26:22PM +0100, Ben Hutchings wrote: > Hello stable maintainers, > > Several Debian users reported a regression after updating to kernel > version 5.10.247. > > Commit f0982400648a ("fbdev: Add bounds checking in bit_putcs to fix > vmalloc-out-of-bounds"), a backport of upstream commit 3637d34b35b2, > depends on vc_data::vc_font.charcount being initialised correctly. > > However, before commit a1ac250a82a5 ("fbcon: Avoid using FNTCHARCNT() > and hard-coded built-in font charcount") in 5.11, this member was set > to 256 for VTs initially created with a built-in font and 0 for VTs > initially created with a user font. > > Since Debian normally sets a user font before creating VTs 2 and up, > those additional VTs became unusable. VT 1 also doesn't work correctly > if the user font has > 256 characters, and the bounds check is > ineffective if it has < 256 characters. > > This can be fixed by backporting the following commits from 5.11: > > 7a089ec7d77f console: Delete unused con_font_copy() callback implementations > 259a252c1f4e console: Delete dummy con_font_set() and con_font_default() callback implementations > 4ee573086bd8 Fonts: Add charcount field to font_desc > 4497364e5f61 parisc/sticore: Avoid hard-coding built-in font charcount > a1ac250a82a5 fbcon: Avoid using FNTCHARCNT() and hard-coded built-in font charcount > > These all apply without fuzz and builds cleanly for x86_64 and parisc64. > > I tested on x86_64 that: > > - VT 2 works again > - bit_putcs_aligned() is setting charcnt = 256 > - After loading a font with 512 characters, bit_putcs_aligned() sets > charcnt = 512 and is able to display characters at positions >= 256 All now queued up, thanks! greg k-h