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 C3A4C4973BA for ; Thu, 17 Sep 2026 16:26:28 +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=1789662390; cv=none; b=j86d0MOcGwoB1l9XpzTiECxmRWGEbI/Qb2yB7qY8XwWLAMp/zH3A8Qq6zFLtnq1wNDqpzk970ZBPSpDup2+KCrFTccPlAKfZ0GUPw2HkPiarFC5TEbuM4RGGgsC2QWbaRHFZgbSH587Op0Ve2bbUABTnunoPU+6geK/zaJVsZbM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789662390; c=relaxed/simple; bh=9SwM0oJHU+uDVEjPpZJeb9d+8QemfJ5PpLAD6hFF+qo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=urnwrK7RV1Lj4rVPmk0SVZm0LmDG6WEg7mgn4ghA771sYOwW61OWJW6fGCPralXE+fkiWD2NHygkZmq3gFzhDuP5exIPw1EcNCkg0cD4q4OpJMOGGjp3OXjSuQaJI0NLgS4hVDtSlAfllLIMYZuzZs/jgA7pFZTl/eCiuxOnRYQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=XHX4TB5D; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="XHX4TB5D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2530F1F00893; Thu, 17 Sep 2026 16:26:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789662388; bh=lur4FXVheqQhT/AXCIyl7Q0LTVuScxqTPgq4uEMun4c=; h=From:To:Cc:Subject:Date:Reply-To; b=XHX4TB5DLYav72+6Jl5//l5F+6GDtsRCDdd7kiVLE/hT9GZY5THIkjxjikIl1lWik WoY/TYQd815LMlFJsYUu97belTnv6SYYAAkaCT1wOKLYBngMuE1XZBvbXbaatCuvRP y4YHK2xuTBHo096lv5Wjnivud6YYXV4JCa+f9l6U= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-90338: serial: amba-pl011: keep console clock enabled for atomic writes Date: Thu, 17 Sep 2026 17:12:48 +0100 Message-ID: <2026091702-CVE-2026-90338-726d@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4209; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=X5+Ts+jm+wuSQj13/VQGfW69RsftUU/CSzpmLSdg4H8=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlrBOYJvI4t/7qNTyh49X6XxRUSuv6/ZHf9Uc//cESqY m6B8vnDHbEsDIJMDLJiiixftvEc3V9xSNHL0PY0zBxWJpAhDFycAjCRizoM89S1b/LqJwRcU8gR uf/wnGgQP+e7DQwLNq9PYdLOfJ/EqdrU653k2OGZOcsEAA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: serial: amba-pl011: keep console clock enabled for atomic writes pl011_console_write_atomic() runs from nbcon atomic context, where sleeping is not allowed. It calls clk_enable(), which takes the common-clk enable_lock. Under PREEMPT_RT that is a sleeping lock: clk_enable_lock() first tries spin_trylock_irqsave(), but on contention falls back to spin_lock_irqsave(). Therefore, an atomic-context printk on an RT kernel with a clk-backed pl011 can trip: BUG: sleeping function called from invalid context at spinlock_rt.c:48 __might_resched from rt_spin_lock rt_spin_lock from clk_enable_lock clk_enable_lock from clk_enable clk_enable from pl011_console_write_atomic ... from vprintk_emit This was found and reproduced on PREEMPT_RT. Arm32 and arm64 DT SoCs are affected; arm64 SBSA/ACPI has no clk, so clk_enable(NULL) short-circuits before the lock. In addition, write_atomic() may be invoked from NMI context and is documented to avoid locking. Removing clk_enable() from the callback also avoids a potentially unsafe NMI acquisition of the common-clock enable_lock. An nbcon atomic-capable console must be printable from any context, so the clock cannot be gated between writes. Enable the clock while the console is available for output: use clk_prepare_enable() in pl011_console_setup(), release it via clk_disable_unprepare() in the console .exit() callback, and drop the per-write clk_enable()/clk_disable() pairs from write_atomic() and write_thread(). When printk suspends consoles, drop the reference after uart_suspend_port() stops console access and restore it before uart_resume_port() -- but only if suspend actually marked the port suspended (a wake-capable tty stays running and must keep its clock), and keep it when console_suspend_enabled is false so no_console_suspend works. The active power cost of keeping the clock enabled is platform-dependent: none where the UART clock is a fixed always-on oscillator, real where it is a gateable clock branch, which then cannot be gated (nor possibly can its parent clocks) while the console is available for output. When serial core actually suspends the port, the reference is released so the clock provider can gate the clock tree. The Linux kernel CVE team has assigned CVE-2026-90338 to this issue. Affected and fixed versions =========================== Issue introduced in 6.15 with commit 2eb2608618ce5878e11bbe68cc8d2699c8f3a81a and fixed in 6.18.52 with commit 5b77848423f4a5a362dcc3caedcdc1a75d0758c3 Issue introduced in 6.15 with commit 2eb2608618ce5878e11bbe68cc8d2699c8f3a81a and fixed in 7.2.6 with commit 2ad24c1d0b939d814a3020f96a667ac2d0394289 Issue introduced in 6.15 with commit 2eb2608618ce5878e11bbe68cc8d2699c8f3a81a and fixed in 7.3-rc1 with commit c0e8cfef754645856374e82c8effd54b7d82002b Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-90338 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: drivers/tty/serial/amba-pl011.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/5b77848423f4a5a362dcc3caedcdc1a75d0758c3 https://git.kernel.org/stable/c/2ad24c1d0b939d814a3020f96a667ac2d0394289 https://git.kernel.org/stable/c/c0e8cfef754645856374e82c8effd54b7d82002b