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 422E1335BA0; Mon, 18 Aug 2025 13:41:14 +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=1755524475; cv=none; b=mDWcZrrrEI0HQDQVqOg3uShfCrdNtPFTP9/G3zj5nsPs/BkpjiScuiIAxY9um/c5aHREXqWNGZAqBg5rjH7F06nDlJKwZJVEBgIoHOl97EfikVY6tVvmeNKQlQ0P76vb8OWhVBgClhKLOG81oUo5CvZ/lWW6KB9533wsdu/qJxw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755524475; c=relaxed/simple; bh=zh+WbuBsNHywc1w+1vQAWCABG5r+2Ccf7JbZ65KLW8w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tMGASONEjXfa4aq/v0smlQmkWDvMSqSFJjcZqB37xYa9oQaItL1V3M883pak0IlOx3ilDeoaew9izq9OJDKbKXkqo7CqsPhiM4mBkVHHsRJKAsUkLqhpptBb8gsCI/Cb5hRrcZky8Fk+nCf4JxYay3R2u/xcd/w6hgwDNQJtWZw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AaWPbbf2; 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="AaWPbbf2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4369CC4CEEB; Mon, 18 Aug 2025 13:41:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755524474; bh=zh+WbuBsNHywc1w+1vQAWCABG5r+2Ccf7JbZ65KLW8w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AaWPbbf2YR+eoeHDOWmq0nk/AXBnNuSKHnopWHbw/01szjErtR/ciXun0Rqi5dd8J dI2CEtHQ74gjAOC5WHoOwEhTIf6npG+mghiQNZTZAibVfWldMwRbri5Q2mtZU2beZG 49WYetePYAQOl5ADsmNtsFjKrqX5VvjiuL+5K6vw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sravan Kumar Gundu , Helge Deller , syzbot+c4b7aa0513823e2ea880@syzkaller.appspotmail.com Subject: [PATCH 6.15 484/515] fbdev: Fix vmalloc out-of-bounds write in fast_imageblit Date: Mon, 18 Aug 2025 14:47:50 +0200 Message-ID: <20250818124517.058375336@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250818124458.334548733@linuxfoundation.org> References: <20250818124458.334548733@linuxfoundation.org> User-Agent: quilt/0.68 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 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sravan Kumar Gundu commit af0db3c1f898144846d4c172531a199bb3ca375d upstream. This issue triggers when a userspace program does an ioctl FBIOPUT_CON2FBMAP by passing console number and frame buffer number. Ideally this maps console to frame buffer and updates the screen if console is visible. As part of mapping it has to do resize of console according to frame buffer info. if this resize fails and returns from vc_do_resize() and continues further. At this point console and new frame buffer are mapped and sets display vars. Despite failure still it continue to proceed updating the screen at later stages where vc_data is related to previous frame buffer and frame buffer info and display vars are mapped to new frame buffer and eventully leading to out-of-bounds write in fast_imageblit(). This bheviour is excepted only when fg_console is equal to requested console which is a visible console and updates screen with invalid struct references in fbcon_putcs(). Reported-and-tested-by: syzbot+c4b7aa0513823e2ea880@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c4b7aa0513823e2ea880 Signed-off-by: Sravan Kumar Gundu Cc: stable@vger.kernel.org Signed-off-by: Helge Deller Signed-off-by: Greg Kroah-Hartman --- drivers/video/fbdev/core/fbcon.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -825,7 +825,8 @@ static void con2fb_init_display(struct v fg_vc->vc_rows); } - update_screen(vc_cons[fg_console].d); + if (fg_console != unit) + update_screen(vc_cons[fg_console].d); } /** @@ -1362,6 +1363,7 @@ static void fbcon_set_disp(struct fb_inf struct vc_data *svc; struct fbcon_ops *ops = info->fbcon_par; int rows, cols; + unsigned long ret = 0; p = &fb_display[unit]; @@ -1412,11 +1414,10 @@ static void fbcon_set_disp(struct fb_inf rows = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres); cols /= vc->vc_font.width; rows /= vc->vc_font.height; - vc_resize(vc, cols, rows); + ret = vc_resize(vc, cols, rows); - if (con_is_visible(vc)) { + if (con_is_visible(vc) && !ret) update_screen(vc); - } } static __inline__ void ywrap_up(struct vc_data *vc, int count)