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Wed, 4 Nov 2026 19:47:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793821643; bh=pUc3XnniVQ5ZOuyDhOysKqrOAZk7AW9/FnAFYC6PjCY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MRau239woFQtdlJcfyIuzdt/Mz7tXpQLHgX2J3HFCxtIoQ7p0t8aEvclvbqPlKOGa EedaHfHccZGMzhB5vcIwAhuyyQDAPau+H/YAUhBdRbtxFhlJqgcxmK2czVG9y5wP7T vy2fA02WDdK3VJ+RlZqpZVnSB9uMz9+ib+VE15vj7NVBBxUCWLKrh6ChnabmilIhZU 3Y5JjgpF66wHdUqRob6tq7eO9hwAVhqpVsM3MxH/8UpRQy6y5G6Z47XYSlSWJ2d5uP 6lZJVoMkctk/0jcZI5OX7z1nQPxzj8u8pGN0oIBxSIKKB6fvv2I5CNKbtMZ1A+Sjdx r3Q7BlsL714Bw== From: Christian Brauner To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Jann Horn , Josef Bacik , Chris Mason , Jeff Layton , NeilBrown , Eric Dumazet , Thomas Gleixner , Al Viro , Jonathan Corbet , Christoph Hellwig , Greg Kroah-Hartman , Joel Granados , Kees Cook , Jan Kara , Jan Kara , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, linux-um@lists.infradead.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, ntfs3@lists.linux.dev, platform-driver-x86@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, netfilter-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, ibm-acpi-devel@lists.sourceforge.net, jfs-discussion@lists.sourceforge.net, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, sparclinux@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-doc@vger.kernel.org, linux-serial@vger.kernel.org, linux-atm-general@lists.sourceforge.net, Takashi Iwai , linux-input@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, linux-modules@vger.kernel.org, linux-debuggers@vger.kernel.org, "Christian Brauner (Amutable)" , Chuck Lever , Jiri Slaby Subject: [PATCH RESEND v2 20/26] tty: sysrq: let procfs copy in writes to /proc/sysrq-trigger Date: Wed, 4 Nov 2026 20:47:08 +0100 Message-ID: <20261104-work-procfs-drivers-v2-20-245e54e87116@kernel.org> In-Reply-To: <20261104-work-procfs-drivers-v2-0-245e54e87116@kernel.org> References: <20261104-work-procfs-drivers-v2-0-245e54e87116@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=1564; i=brauner@kernel.org; h=from:subject:message-id; bh=xA04tAm65fsCtMg0xl0tBqqUoHOUL5b4F/HBKwEi4qU=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS97up5wHzVwMj/4s+/qsc0lZwe6RUvWPryURRj4B+1W WLHtl+Y3FHKwiDGxSArpsji0G4SLrecp2KzUaYGzBxWJpAhDFycAjCRvW8Z/srfZV/202bOs6pv bO3FhjJLqzofzqvaU2easvxKpvXzafoMf3jnJ8cnHTZnrf/9WuLLwePxp5qz7/ZoyYesNj+yaqb 8JzYA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Content-Transfer-Encoding: 8bit X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" X-Spam-Status: No, score=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Implement ->proc_write_buf() so procfs copies in what is written before it pins the entry, and handle the keys from that copy. Writes larger than PAGE_SIZE - 1 bytes fail with -EINVAL now. They used to trigger the first key, or all of them in bulk mode. procfs allocates the copy, which is as small as the write, opening the file allocated as much already. Reviewed-by: Jiri Slaby Signed-off-by: Christian Brauner (Amutable) --- drivers/tty/sysrq.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index f4571d05b496..99363e1b59ed 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -1200,17 +1200,14 @@ EXPORT_SYMBOL(unregister_sysrq_key); * However, if the first character is an underscore, * all characters are processed. */ -static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, +static ssize_t write_sysrq_trigger(struct file *file, char *buf, size_t count, loff_t *ppos) { bool bulk = false; size_t i; for (i = 0; i < count; i++) { - char c; - - if (get_user(c, buf + i)) - return -EFAULT; + char c = buf[i]; if (c == '_') bulk = true; @@ -1225,7 +1222,7 @@ static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, } static const struct proc_ops sysrq_trigger_proc_ops = { - .proc_write = write_sysrq_trigger, + .proc_write_buf = write_sysrq_trigger, .proc_lseek = noop_llseek, }; -- 2.53.0