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Mon, 2 Nov 2026 15:05:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793631915; bh=/usm8OdHJAbA2hfj2koEwGvMkvG3A+8dTBDDaCx7vxs=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=GwaRh4oGylUX6g6CEqPXd69Ibpr3KQmakI0Nld+n+JLGApofu8ygx4WwNRI60EvYf DSOWIV++3VospwIjrvRsrg0mfaY7gRgUeihp43Au6D6HgV7Xv8KolBhRU7xFnfQdC1 T7WNrsjJHzUGFZHB3CY8jnJ95TWdIrLVspjluFdHIKRvTNa2WFPvdVn+u5eXib/14W 9Mf7AL8v6CpiYBfwScgPVzymR7ApEayesBtx54t9q1NbuhjbVtR1b4mKqnuDg4Wxmn KCXgiDmRsG7or4q0U1UicO9HEaUHCZVEQAI8u1qAq9b4HgJ4PMYdAOqXF8iMKD4/CK FsxoDOM8JDDag== From: Christian Brauner Date: Mon, 02 Nov 2026 16:01:38 +0100 Subject: [PATCH RFC 11/22] um: let procfs copy in writes 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-v1-11-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() for the mconsole and exitcode files so procfs copies in what is written before it pins the entry. Writes larger than PAGE_SIZE - 1 bytes fail with -EINVAL now. exitcode parses procfs' copy as is, so it no longer stops at the first six bytes of what is written. Signed-off-by: Christian Brauner (Amutable) --- arch/um/drivers/mconsole_kern.c | 11 ++--------- arch/um/kernel/exitcode.c | 14 ++++---------- 2 files changed, 6 insertions(+), 19 deletions(-) diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c index f01b7d8a07bc..a4370470286f 100644 --- a/arch/um/drivers/mconsole_kern.c +++ b/arch/um/drivers/mconsole_kern.c @@ -769,21 +769,14 @@ static int __init mconsole_init(void) __initcall(mconsole_init); static ssize_t mconsole_proc_write(struct file *file, - const char __user *buffer, size_t count, loff_t *pos) + char *buf, size_t count, loff_t *pos) { - char *buf; - - buf = memdup_user_nul(buffer, count); - if (IS_ERR(buf)) - return PTR_ERR(buf); - mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count); - kfree(buf); return count; } static const struct proc_ops mconsole_proc_ops = { - .proc_write = mconsole_proc_write, + .proc_write_buf = mconsole_proc_write, .proc_lseek = noop_llseek, }; diff --git a/arch/um/kernel/exitcode.c b/arch/um/kernel/exitcode.c index c71657df38f5..8f76e3b20c18 100644 --- a/arch/um/kernel/exitcode.c +++ b/arch/um/kernel/exitcode.c @@ -32,18 +32,12 @@ static int exitcode_proc_show(struct seq_file *m, void *v) } static ssize_t exitcode_proc_write(struct file *file, - const char __user *buffer, size_t count, loff_t *pos) + char *buffer, size_t count, loff_t *pos) { - char *end, buf[sizeof("nnnnn\0")]; - size_t size; + char *end; int tmp; - size = min(count, sizeof(buf) - 1); - if (copy_from_user(buf, buffer, size)) - return -EFAULT; - buf[size] = '\0'; - - tmp = simple_strtol(buf, &end, 0); + tmp = simple_strtol(buffer, &end, 0); if ((*end != '\0') && !isspace(*end)) return -EINVAL; @@ -53,7 +47,7 @@ static ssize_t exitcode_proc_write(struct file *file, static const struct proc_ops exitcode_proc_ops = { .proc_show = exitcode_proc_show, - .proc_write = exitcode_proc_write, + .proc_write_buf = exitcode_proc_write, }; static int make_proc_exitcode(void) -- 2.53.0