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=1793210792; b=lbqs7ktwpVZzOkf+kUDBmFJnXplr5kL/X419xZ5MejkSKdP9QwKcwNlOcn4khNNVAel7 ObntyOY682EKZ9JymBm5U1aqq0ZNurHKkMsCHax+mliPtkEGFIjXECfkxoSxQ6HH+siKZ dztmynJw77OKSFa1HUgZfC6JVVFhm2XGmlRdcEvlV/g0qv3F96o/ULJkfouKwYuEkccM1 8ZqQNkJprFPKDuEtl68urI1LGs8ZkrR9j2nzvXq1eiHxoaP5kuJqW5004nhXk89WCehzj 46j0GtxqZQxXLQm/oQ7oArS/M5AnU29aHN91hO+x0AfnosxDucxJ3MUkXXLIv0g/3cQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793210792; 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=2VG31RdozhImAPM9iMxYTMf/GbtdW+WHsq6xM38YiBw=; b=FuhlguwfkszOPZZkSJTrTQoltuI5KuMR5QvcZE9t/qSNMBOS31exMf/sq3rNR8Eo6dsr 32pbZkwJ6F6dps+nrNzHxzynJ1E1dT1pnZ7WFsrrAlXlj0IogiFjfoxQ7/IehIY9Rkc0a iRwoqfHkvJLAP35NAvOjrNR44tVmdBGHmg7kw9ILxGs5cYrCPUQf5aPTbjbi5JRxO3jtC GD80Imt+ixWfAyv1A5ByuyS/LFhebc+VTU1oKtwVPO6wQpPh/ODcWAECaLomwe/7Yvtz8 EA3H9S09Ii6W1wWwJzcykmjvelhxo85HB/qKappFpj6PTC14fzJyIifz6cg9gZqAM+w== 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=JfiGmhKs; 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 A8354606A323; Wed, 28 Oct 2026 18:06:31 +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=JfiGmhKs Received: by smtp.kernel.org (Postfix) with ESMTPSA id 040F81F01825; Wed, 28 Oct 2026 18:06:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793210791; bh=2VG31RdozhImAPM9iMxYTMf/GbtdW+WHsq6xM38YiBw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JfiGmhKs42+eaBnnDEOlcbxAA9JjTaMtIKMiTiFsjtMv6UzE9bnh89wjAEmCgflvS GAGt3qVKxQZGIi25qQvslX3Ya+DNIOfWqb039tLSBF6bVHGytUHsdJcA/1L4dlQ54A 08MKPtQj3Y3GrrTFTdft3T6BRVbmsXiGH+sBNQmo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Zizhi Wo Subject: [PATCH 5.15 150/571] vt: skip screen update for DEC alignment test on backgroup consoles Date: Wed, 28 Oct 2026 17:54:57 +0100 Message-ID: <20261028170011.575741942@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@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 5.15-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: