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Mon, 2 Nov 2026 15:05:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793631956; bh=08oqN1TE6XF/zda2aaIy/jJ7rzXSJoF5jY3Jq8EQn3I=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=esP1NXiJtkWIwe0zxy+yALxJft8aenVVlvrmNyeWEmPwwMUFoGj4vVXV8t6fYRCCr PUrWrFhkorqvWNCdJaSQMLf/MWYFqMu/fjhYRkfg/ntu2jTry0OdIErXKyYUuaX9b2 s/YJB0wieY9b+/J0uqo3gTDUZNa/iAbOQ22VE6vCDejVVu2QvhNeen/wYMi1uUBddD otQ6tttXu5fna5CmPdbWZ3/5LvyLR1HZD3qs4y3l163vI5ZM0FWutUhg0hU7z8iAs6 9fnCJsDMduAv+8gXV1qLG+g/a4WXlmT3vfPCv0fZZv3ZT7nfZmWkFHzOiAfiEsinuc E814TEauo1aaQ== From: Christian Brauner Date: Mon, 02 Nov 2026 16:01:40 +0100 Subject: [PATCH RFC 13/22] x86/mtrr: let procfs copy in writes to /proc/mtrr X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , Precedence: list X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261102-work-procfs-arch-v1-13-c9492ab08480@kernel.org> References: <20261102-work-procfs-arch-v1-0-c9492ab08480@kernel.org> In-Reply-To: <20261102-work-procfs-arch-v1-0-c9492ab08480@kernel.org> 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 X-Mailer: b4 0.17-dev X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, 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 parse the command from that copy. Writes larger than PAGE_SIZE - 1 bytes fail with -EINVAL now. Signed-off-by: Christian Brauner (Amutable) --- arch/x86/kernel/cpu/mtrr/if.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/mtrr/if.c b/arch/x86/kernel/cpu/mtrr/if.c index 9510e01d5103..038e2dc38797 100644 --- a/arch/x86/kernel/cpu/mtrr/if.c +++ b/arch/x86/kernel/cpu/mtrr/if.c @@ -91,7 +91,7 @@ mtrr_file_del(unsigned long base, unsigned long size, * "base=%Lx size=%Lx type=%s" or "disable=%d" */ static ssize_t -mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos) +mtrr_write(struct file *file, char *buf, size_t len, loff_t * ppos) { int i, err; unsigned long reg; @@ -103,9 +103,8 @@ mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos) memset(line, 0, LINE_SIZE); len = min_t(size_t, len, LINE_SIZE - 1); - length = strncpy_from_user(line, buf, len); - if (length < 0) - return length; + length = strnlen(buf, len); + memcpy(line, buf, length); ptr = line + length - 1; if (length && *ptr == '\n') @@ -397,7 +396,7 @@ static int mtrr_open(struct inode *inode, struct file *file) static const struct proc_ops mtrr_proc_ops = { .proc_show = mtrr_seq_show, .proc_open = mtrr_open, - .proc_write = mtrr_write, + .proc_write_buf = mtrr_write, .proc_ioctl = mtrr_ioctl, #ifdef CONFIG_COMPAT .proc_compat_ioctl = mtrr_ioctl, -- 2.53.0