From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 7024339F16B for ; Sun, 4 Oct 2026 17:39:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791135546; cv=none; b=Zjpc13xPr1SeI5C1kyTt4TjSbOCoMlEtBR8kB/wtvTwRavCsbJH1u4nqjSLIiCF2fWAtAh2vSXk4yI0juIi5+fEdrljDSz5qbR4Wn3ibshJgd98wVyHMMuMNJVc9ONj9ZDXNFUrqD3BAse48AFq19tsXscsom5Rk0qireDzKHZg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791135546; c=relaxed/simple; bh=+VNfsMK96Xcv9FRbn0fqWwjBWZ1jbumT5jLl3yrmdYQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aiFxJPbA5kXj+gUJMi24ylp0OQu9UcWMJJLnjApLesXKMuwJNQpSv4xHvYp82hJd53sSPEsKVJACJCdkh+T25iFSqFlh0ZxmjJS6u3I0hmeh5yQv9ISyOW0wz2Jpd7ijGC26b0u69W36/pKDkKK87Vq1PYWIquSzBtcwiY4C95o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oDUq4evX; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="oDUq4evX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CEDA31F00893; Sun, 4 Oct 2026 17:39:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791135545; bh=VbIX2FBU8ElTmA0ZoIOeSKq3qO3y+REc9lIXx6cTvkw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=oDUq4evXSPLXM54CIqDIAZS3adFnki0ovxSybfx8oMdUo9zjVOJoJHU0riloYUEsh 69oC2yW5eoCanRkmq5bxXBhjqy2vXSQ9Uy1bRSnSsGgEFBAEH6n7n+JQ/lBR3H2/Ln 8Hcvth8oDF89nzqhqcbQyalw2KYrAxljrunv/ZcP/qO1LDpohUouXKNaOOE2LQ05f+ nr7sTXrb+MCnqAw+8cs2v7JAlpFxt6MylM7jJRp8/P6RLcTzj56DPjtr2z/eHslLzz wJJCYnh8Y/Pw45NBvsdLQnQQV5HuNxIomHpZMSFHe42jaGN7MyBYrMgITgS/H00lA+ X1G03HxtU7U2w== From: Sasha Levin To: stable@vger.kernel.org Cc: "Jiri Slaby (SUSE)" , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 6.12.y 2/3] tty/vt: use guard()s Date: Sun, 4 Oct 2026 13:38:58 -0400 Message-ID: <20261004173840.989210-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261004173840.989210-1-sashal@kernel.org> References: <2026100453-thorn-hurricane-763b@gregkh> <20261004173840.989210-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Jiri Slaby (SUSE)" [ Upstream commit e730c373b6ff16a177e132859bf6ea4dbb15105f ] Having all the new guards, use them in the vt code. This improves readability, makes error handling easier, and marks locked portions of code explicit. A local free_page_ptr __free guard is introduced for __get_free_page/free_page (with proper casts). This could be made public in include/. But I am not sure if there are more possible users, so keeping completely private here. Signed-off-by: "Jiri Slaby (SUSE)" Link: https://lore.kernel.org/r/20250814072456.182853-16-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman Use scope-based console locking and buffer cleanup in vcs_write() so error paths can return directly while releasing both resources. Limit the conversion to the function needed by the follow-up console pointer reload fix. Omit the other guard conversions, including the selection changes whose context assumes bracketed-paste support. Allocate the page-sized copy buffer with kmalloc() and reuse the existing kfree cleanup guard instead of introducing a new cleanup helper. Declare the buffer before the console guard so the console is unlocked before the buffer is freed, preserving the original cleanup order. [ sashal: REDUCED BACKPORT of e730c373b6ff: carries 29/414 upstream changed lines; not carried: drivers/tty/vt/consolemap.c:con_set_trans_old(), drivers/tty/vt/consolemap.c:con_get_trans_old(), drivers/tty/vt/consolemap.c:con_set_trans_new(), drivers/tty/vt/consolemap.c:con_get_trans_new(), drivers/tty/vt/consolemap.c:con_clear_unimap(), drivers/tty/vt/selection.c:sel_loadlut(), drivers/tty/vt/selection.c:set_selection_kernel(), drivers/tty/vt/selection.c:paste_selection(), +28 more ] Stable-dep-of: 226bd5603371 ("vc_screen: reload vc pointer before if (ret) in vcs_write() to avoid UAF") Signed-off-by: Sasha Levin --- drivers/tty/vt/vc_screen.c | 29 +++++++++-------------------- 1 file changed, 9 insertions(+), 20 deletions(-) diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c index 2536635153552..a59d2006b1a99 100644 --- a/drivers/tty/vt/vc_screen.c +++ b/drivers/tty/vt/vc_screen.c @@ -591,7 +591,6 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { struct inode *inode = file_inode(file); struct vc_data *vc; - char *con_buf; u16 *org0, *org; unsigned int written; int size; @@ -602,7 +601,7 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) if (use_unicode(inode)) return -EOPNOTSUPP; - con_buf = (char *) __get_free_page(GFP_KERNEL); + char *con_buf __free(kfree) = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!con_buf) return -ENOMEM; @@ -611,22 +610,18 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) /* Select the proper current console and verify * sanity of the situation under the console lock. */ - console_lock(); + guard(console_lock)(); attr = use_attributes(inode); - ret = -ENXIO; vc = vcs_vc(inode, &viewed); if (!vc) - goto unlock_out; + return -ENXIO; size = vcs_size(vc, attr, false); - if (size < 0) { - ret = size; - goto unlock_out; - } - ret = -EINVAL; + if (size < 0) + return size; if (pos < 0 || pos > size) - goto unlock_out; + return -EINVAL; if (count > size - pos) count = size - pos; written = 0; @@ -651,8 +646,7 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) */ if (written) break; - ret = -EFAULT; - goto unlock_out; + return -EFAULT; } } @@ -664,15 +658,13 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) if (!vc) { if (written) break; - ret = -ENXIO; - goto unlock_out; + return -ENXIO; } size = vcs_size(vc, attr, false); if (size < 0) { if (written) break; - ret = size; - goto unlock_out; + return size; } if (pos >= size) break; @@ -702,9 +694,6 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) if (written && vc) vcs_scr_updated(vc); -unlock_out: - console_unlock(); - free_page((unsigned long) con_buf); return ret; } -- 2.53.0