From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793212575; b=stpty9yUiK6ZkKaXEEc7+vcCer2nSzbAj1pWI3o4Vh+K9Dayaty5VtOeKUL8tBcEcRPn 4YQL6f0IJQsG47vubEiZjImpz2Pt60gAWKfjecOWu8KmM+LLeRyeXjlr/24qYNyc93yZz 4oxiz9G9GmbSQQKrqOx6e/vh5/qg2uaNnVA9onT6J6r4Y0xbrEJITv9cPWBAs2Ok2Nw9j ClTSuwvD0RdGGu2DUUvMCLDYMLI0jrpBV9IwZkm+lE1+pn/ROT6y8l0eBlQ4frt5/GHSa 1Wd3hgphY7QNS4li4RUs46QO3vYNzK+QrlArUT3jU1YIFS4Pte/lI+XjJzEiwxF5CnA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793212575; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=QhUTHLkz5UOhEJ3hdem61oXU/xxbZQa63W5VzngBx8I=; b=OpKZSxguTSV7KAZXGp0+KuFfYhpqGkEjTQmWrSI6AAEz0onlJTCMassgEZjjXZAX9tQS hxpj76fr2DgotJGQOGI8VzX3PKZ2b3BIxa+ULOP2ZGl9YVobaCbkAVNXeFFi3XSfnn2dT F+9I5HgFisrsVc2ZiW+ZlTuamkuevC3aU5ZgL0C+c1LKmJCrA2GJZlAvnqGBrkNWVMCG8 QF0/RfawhekrXIw7xe6UOvDcznNYGIMRqgM+fC2Q07FW43rRMzqEMQK9ccYxQ3TzLZ7s8 3hPpCaVGg+j/LrKgrCXgS44iA33riMPbMBxI1KO3j0GaBggeVb+NG8TSWNS3FdXSxEA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=HwwG54DX; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4D339606A31C; Wed, 28 Oct 2026 18:36:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=HwwG54DX Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D5F51F01825; Wed, 28 Oct 2026 18:36:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793212575; bh=QhUTHLkz5UOhEJ3hdem61oXU/xxbZQa63W5VzngBx8I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HwwG54DX5TwNfKLWzQfwtfcLQaeaZP0EeUfvuw3k7fbGn6cO4MGYUJJ+1Wdm6gG+z 6nVkG4U7nj4fzod/9pK4fLaC7XqUkbcADO4tKbib37GSQVNj7lCkREoN3XNZY2wauf sT/O+wFCtiUdhdLHxeDAKmDMuH+xuxsK62s4u+o0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Zizhi Wo Subject: [PATCH 6.1 0200/1887] vt: skip screen update for DEC alignment test on backgroup consoles Date: Wed, 28 Oct 2026 17:38:16 +0100 Message-ID: <20261028170503.786996141@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170459.200466217@linuxfoundation.org> References: <20261028170459.200466217@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zizhi Wo commit 0928ed9bd7946baee911efa401088697836e3b1e upstream. [BUG] Recently, we encountered a KASAN warning as follows: BUG: KASAN: slab-out-of-bounds in fb_pad_aligned_buffer+0x11f/0x140 Read of size 1 at addr ff1100015fd9f6a4 by task tty_fbcon_oob/1239 CPU: 7 UID: 0 PID: 1239 Comm: tty_fbcon_oob Not tainted 7.3.0-rc1 #100 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014 Call Trace: ... kasan_report+0xf0/0x120 fb_pad_aligned_buffer+0x11f/0x140 ccw_putcs+0x86c/0xa80 fbcon_putcs+0x338/0x410 do_update_region+0x21d/0x450 do_con_write+0x1e0e/0x4880 con_write+0x13/0x80 n_tty_write+0x374/0x1010 file_tty_write.isra.0+0x404/0x7a0 ... reproduce: 1) open /dev/tty0, set a KDFONTOP ioctl with op.op = KD_FONT_OP_SET, op.width = 8 and op.height = 16 (visible VC1) 2) open /dev/tty1, set a KDFONTOP ioctl with op.op = KD_FONT_OP_SET, op.width = 28 and op.height = 24 (invisible VC2) 3) echo 3 > /sys/devices/virtual/graphics/fbcon/rotate_all 4) write EShash8(esc hash8) to tty1 [CAUSE] All VCs render to the framebuffer. setfont only modifies the target VC's font without resizing the framebuffer backing buffer (par->rotated.buf); the buffer is only resized for the visible VC (fbcon_do_set_font -> ... -> vc_do_resize -> update_screen). This relies on the con_should_update() check performed before every update_region(). However, the ESC # 8 path (do_con_trol -> do_update_region) omits the con_should_update() check. After changing the font size of an invisible VC, do_update_region() fills using the new font size against a buffer that was never resized, causing an out-of-bounds access. [FIX] Only push the update when the console is visible and not blanked, add the con_should_update() check in the do_con_trol() like every other call site of do_update_region() (update_region(), invert_screen(), ...). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable Signed-off-by: Zizhi Wo Link: https://patch.msgid.link/20260905064337.3083103-1-wozizhi@huaweicloud.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/vt/vt.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -2543,7 +2543,8 @@ static void do_con_trol(struct tty_struc csi_J(vc, 2); vc->vc_video_erase_char = (vc->vc_video_erase_char & 0xff00) | ' '; - do_update_region(vc, vc->vc_origin, vc->vc_screenbuf_size / 2); + if (con_should_update(vc)) + do_update_region(vc, vc->vc_origin, vc->vc_screenbuf_size / 2); } return; case ESsetG0: