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 433B2303C91; Wed, 3 Dec 2025 15:39:03 +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=1764776343; cv=none; b=Bx4YROOczk19j0NWVmCSqB1RoL6ewQQr7k/D+EpB3ncYNQ9b3T5jnL8ekON6NXIrOgp0XoUJ3CXTmrsrKAENuQ79kkEkw91TAdW6EiBzc1JDnNf31ebRuXgsjiLJsy6WJwOqf1DKfzcYUyuYN3X8BRA4xBsUQ2WqWiuxYPFqHCc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764776343; c=relaxed/simple; bh=fb0VWTeNhYJ8ZF+/h9CMXC10e/pux0J2gzTYrIhuXq8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sfCxlMKZgkoSqazpLcs6bq5btDk4/jzCL6nLbqQkz4IHFOzRLnxzOEHfr8ZouUNIB0t6B+5jh9zAahI27qnBPqFMo83XPhxkjQvcw2L4hsW9b545cl1JpbYHsnV3j+YWd1UrQRQh/ArSx6zl0DSkQ+NDO9kUZfOFaOyJuiHJUTw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BR51Ef06; 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="BR51Ef06" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A610BC4CEF5; Wed, 3 Dec 2025 15:39:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1764776343; bh=fb0VWTeNhYJ8ZF+/h9CMXC10e/pux0J2gzTYrIhuXq8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BR51Ef06usPsR5inUgUOsO1+JB5gZ1pE+OanFI/M1daAfcx/fmGqG9g5hYJCeY9mL b2STp6NR8RwLTFSITYFRmZU6m5afhDkopbzMk5nuK+8wkd5Es294mrnZBye9Ieib1C 7TCQ14NQ0vRj2W2M5iSbjfpnvtEdI8TlSbZrkLBg= 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 5.10 154/300] fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds Date: Wed, 3 Dec 2025 16:25:58 +0100 Message-ID: <20251203152406.322245962@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251203152400.447697997@linuxfoundation.org> References: <20251203152400.447697997@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 5.10-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 4e774010d09f6..7c2fc9f83a848 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