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 12F0C30C63B; Tue, 11 Nov 2025 01:40:46 +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=1762825246; cv=none; b=iQthSUekMVVuyzD/Ljlor5c/ZhmTXKbmzrVNVPd5r8umVhimFV+tMixurwcyIsb5hnmM/6JJ5J00S16wWSnT8+NWdVDXfpFCuTPdwKwAW4TBTzF6d7fP1XusST3+9PbsztSWd2K8sMm+14sdlNaLSOTe4H+31M/W4/0ldKuSvZw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762825246; c=relaxed/simple; bh=039M/5pxkti42kFAJLLzyH+5gZij9jik6ctY2Mohj4w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=e5mk+1ve7bLtUHOuf6pzmHeihTUn+ZUXMrSFM1PU+n+AVO0CPIe4ijjuGIVCLUdnAekMvfdPCltvAWQ6/oqsA0MyiimjRepHpmYbs3VlP5jbNcTN3neOj3qjL1Vlzryri1jLiLrvKyg/JGwjY6UAWLp9+UiAcwNbSF2TfzaaCcs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=buY3uGQf; 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="buY3uGQf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A75C9C16AAE; Tue, 11 Nov 2025 01:40:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1762825245; bh=039M/5pxkti42kFAJLLzyH+5gZij9jik6ctY2Mohj4w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=buY3uGQf5Nwn9vcHJ7kyzLtuZGxhgbejaxdjg/QxZbz+apSgK7BHqy6FGgAAiiVLX 3tEnQx3JGSgOJOuxCD4HWDGf1pZ7n1Y2PFFQg+RF7Ytu3lcZC4oXo6HfCv+ht3XxGr O5Cgj6Ny+VlJKU4wXjPkBiqJriTPpNEMKJ2wULIg= 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 6.17 723/849] fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds Date: Tue, 11 Nov 2025 09:44:53 +0900 Message-ID: <20251111004553.914117398@linuxfoundation.org> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20251111004536.460310036@linuxfoundation.org> References: <20251111004536.460310036@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.17-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 2e46c41a706a2..dc5ad3fcc7be4 100644 --- a/drivers/video/fbdev/core/bitblit.c +++ b/drivers/video/fbdev/core/bitblit.c @@ -168,6 +168,11 @@ 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) @@ -181,6 +186,18 @@ 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