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Fri, 06 Nov 2026 09:21:19 -0800 (PST) Received: from pathway.suse.cz ([176.114.240.130]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4b6e24012c3sm68262245e9.13.2026.11.06.09.21.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Nov 2026 09:21:19 -0800 (PST) From: Petr Mladek To: John Ogness Cc: Sergey Senozhatsky , Steven Rostedt , Marcos Paulo de Souza , Chris Down , Naveen Kumar Chaudhary , printk@lists.linux.dev, linux-kernel@vger.kernel.org, Petr Mladek Subject: [PATCH v6 05/16] printk: Do not accept an empty name or devname as a preferred console Date: Fri, 6 Nov 2026 18:19:41 +0100 Message-ID: <20261106171952.207909-6-pmladek@suse.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261106171952.207909-1-pmladek@suse.com> References: <20261106171952.207909-1-pmladek@suse.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The current code for storing preferred consoles does not expect the case when an empty string is passed via @name or @devname. Empty console driver name does not make any sense. Avoid handling such entries completely. Suggested-by: Chris Down Reviewed-by: Petr Mladek --- kernel/printk/printk.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index b7543fea865b..6bba67e142e1 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2558,7 +2558,9 @@ asmlinkage __visible void early_printk(const char *fmt, ...) * * The function adds or updates an entry in preferred_consoles[] array. Also * it updates some global variables which are used to make the right decisions - * in register_console(). + * in register_console(). Finally, it enforces some rules: + * + * 1. Do not accept empty @name or @devname. */ static int add_or_update_preferred_console(unsigned int i, const char *name, const short idx, @@ -2576,6 +2578,11 @@ static int add_or_update_preferred_console(unsigned int i, if (!name && !devname) return -EINVAL; + if ((name && !name[0]) || (devname && !devname[0])) { + pr_err("Adding a preferred console with an empty name\n"); + return -EINVAL; + } + /* * We use a signed short index for struct console for device drivers to * indicate a not yet assigned index or port. However, a negative index -- 2.56.0