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 ADC0F24EA90; Mon, 1 Dec 2025 11:30:24 +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=1764588624; cv=none; b=I+0GCbfgK1uhDeSrzMYsOsNb+W+kBLjbditZ78jM4B3zHFxjefPDdhp0SXjbHUBNU/wocAKgPQeoGreQJqIkD9wgWlnU+ewPobHKbyHVc3yYG83nCEy0Mla1v4dZdynnrahJoTlYSyo93VCFBDtaTW23dSajkNCWbB/SkEdBNTk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764588624; c=relaxed/simple; bh=0k6lTdUIyXiDnEAtRDSvZaCtYOc/nhi+S3cQoSPhMrI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NsHZOPlvnnSSkLYi+xZbdmQNU/Xv1vEmVz2kc4rtthY8WWNx0yZXZIkJtkw+SfaBOCcwdHUMdGNpQUmmRhGu72kGfYiwg/51ADq8BiosS18K8P3NcldMCrvXEIxXN23c9hkfVN2mPEtZgWVOG2nBncxvyU+3If/KAPl+Lt2nVuw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=N9JwCwdo; 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="N9JwCwdo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3664BC4CEF1; Mon, 1 Dec 2025 11:30:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1764588624; bh=0k6lTdUIyXiDnEAtRDSvZaCtYOc/nhi+S3cQoSPhMrI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N9JwCwdoPw0yZOUfFJKYEbhFPqGu+icegKgaFGUULI+Ab+l6HNHve+UAC6yVi7EPX nh6HJLyVUwOL0QuNTbgrknVWiEp3lzLIyVjyqQrvtHFgSY5Dtw0B+gN81CcXErvAo0 NFdvNEpfepiAm6mm5SoszNXviRC546fD/UGAr4ik= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+48b0652a95834717f190@syzkaller.appspotmail.com, Helge Deller , Albin Babu Varghese , Sasha Levin Subject: [PATCH 5.4 112/187] fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds Date: Mon, 1 Dec 2025 12:23:40 +0100 Message-ID: <20251201112245.278694839@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251201112241.242614045@linuxfoundation.org> References: <20251201112241.242614045@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Albin Babu Varghese [ Upstream commit 3637d34b35b287ab830e66048841ace404382b67 ] Add bounds checking to prevent writes past framebuffer boundaries when rendering text near screen edges. Return early if the Y position is off-screen and clip image height to screen boundary. Break from the rendering loop if the X position is off-screen. When clipping image width to fit the screen, update the character count to match the clipped width to prevent buffer size mismatches. Without the character count update, bit_putcs_aligned and bit_putcs_unaligned receive mismatched parameters where the buffer is allocated for the clipped width but cnt reflects the original larger count, causing out-of-bounds writes. Reported-by: syzbot+48b0652a95834717f190@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=48b0652a95834717f190 Suggested-by: Helge Deller Tested-by: syzbot+48b0652a95834717f190@syzkaller.appspotmail.com Signed-off-by: Albin Babu Varghese Signed-off-by: Helge Deller Signed-off-by: Sasha Levin --- drivers/video/fbdev/core/bitblit.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/drivers/video/fbdev/core/bitblit.c b/drivers/video/fbdev/core/bitblit.c index 99a4f048b96ac..75c20f8e58e33 100644 --- a/drivers/video/fbdev/core/bitblit.c +++ b/drivers/video/fbdev/core/bitblit.c @@ -169,6 +169,11 @@ static void bit_putcs(struct vc_data *vc, struct fb_info *info, image.height = vc->vc_font.height; image.depth = 1; + if (image.dy >= info->var.yres) + return; + + image.height = min(image.height, info->var.yres - image.dy); + if (attribute) { buf = kmalloc(cellsize, GFP_ATOMIC); if (!buf) @@ -182,6 +187,18 @@ static void bit_putcs(struct vc_data *vc, struct fb_info *info, cnt = count; image.width = vc->vc_font.width * cnt; + + if (image.dx >= info->var.xres) + break; + + if (image.dx + image.width > info->var.xres) { + image.width = info->var.xres - image.dx; + cnt = image.width / vc->vc_font.width; + if (cnt == 0) + break; + image.width = cnt * vc->vc_font.width; + } + pitch = DIV_ROUND_UP(image.width, 8) + scan_align; pitch &= ~scan_align; size = pitch * image.height + buf_align; -- 2.51.0