From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1478A2737FF; Wed, 16 Jul 2025 19:47:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752695246; cv=none; b=YgY5Xo/2496BkVw3RoSlAKrNjsbSIDI+7x9OyFFZFfvXj9lv8F3RlSByIXLbxjugsemcuwp75aMdQaDS7NpQge6tnyMJQ2mpHSMTBmA3Q+mQEIJnYxCTCrkF/yei21BRBR8tP32TvqNY1SzzARSbYWENpG96yZx23L1CXJdDkj0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752695246; c=relaxed/simple; bh=JyKUvJx6D7rN3PbMXsN8uzlXP0z8IlxTSoGvQpStzrk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=glHzY5Knsxtef/6yO1QP12u4S2uYZU0oh+lUiOT2EBWFL+7KwPtms0hWhJdEL35YYeUwqEZlVjfQ/Ft3+tsQQv8Woug2dfZi+GIav5xIyCV2X5iLdFXkhZj7+mxlzirKHf9i688j8WQoD9gtOGcW7PMa7xIROvJze4Nv5oS955k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jLWaX7JB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jLWaX7JB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A564EC4CEE7; Wed, 16 Jul 2025 19:47:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752695245; bh=JyKUvJx6D7rN3PbMXsN8uzlXP0z8IlxTSoGvQpStzrk=; h=Date:Reply-To:Subject:To:Cc:References:From:In-Reply-To:From; b=jLWaX7JBUkLJXJ9YpuORgUFFGvOhuPGtNIbSo2ClwAPDjyvRmnuJmkEJgDfDcG9Uq FYZ5HH8OQ2nJeoL3E0ejqWxQZHFUhkYK9pUkhFzX2ZpOJJGHmSHBlilgQ2E9UTfRAK cRkZaEURFG8+HU0NqKIj4LZitt4nrSL/L+j/4JRItzJFU4OVFRtpcO1y06jZsSbw2H NGUZzGqOPXyXruiLwcmkpuHaf+95wOROQ1MioODNgWD7a7XM8OuF8Cl6GjAtZs4XeK OZ+Ddfh9VeTxBa+1SM0WqnaKCq0QlXy5wxIm7fx4Ho6DQ6NXO68hnT9IySbQejBuQ9 mUrHFIdXKV6qg== Message-ID: <0dee8b80-1bb9-4d34-9b39-344e391d56f4@kernel.org> Date: Wed, 16 Jul 2025 21:47:19 +0200 Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: Daniel Gomez Subject: Re: [PATCH 1/5] module: Prevent silent truncation of module name in delete_module(2) To: Petr Pavlu , Luis Chamberlain , Sami Tolvanen , Daniel Gomez Cc: linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250630143535.267745-1-petr.pavlu@suse.com> <20250630143535.267745-2-petr.pavlu@suse.com> Content-Language: en-US From: Daniel Gomez Organization: kernel.org In-Reply-To: <20250630143535.267745-2-petr.pavlu@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 30/06/2025 16.32, Petr Pavlu wrote: > Passing a module name longer than MODULE_NAME_LEN to the delete_module > syscall results in its silent truncation. This really isn't much of > a problem in practice, but it could theoretically lead to the removal of an > incorrect module. It is more sensible to return ENAMETOOLONG or ENOENT in > such a case. > > Update the syscall to return ENOENT, as documented in the delete_module(2) > man page to mean "No module by that name exists." This is appropriate > because a module with a name Including the NUL byte... > longer than MODULE_NAME_LEN cannot be loaded > in the first place. > > Signed-off-by: Petr Pavlu > --- > kernel/module/main.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/kernel/module/main.c b/kernel/module/main.c > index 413ac6ea3702..933a9854cb7d 100644 > --- a/kernel/module/main.c > +++ b/kernel/module/main.c > @@ -751,14 +751,16 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user, > struct module *mod; > char name[MODULE_NAME_LEN]; > char buf[MODULE_FLAGS_BUF_SIZE]; > - int ret, forced = 0; > + int ret, len, forced = 0; > > if (!capable(CAP_SYS_MODULE) || modules_disabled) > return -EPERM; > > - if (strncpy_from_user(name, name_user, MODULE_NAME_LEN-1) < 0) > - return -EFAULT; > - name[MODULE_NAME_LEN-1] = '\0'; > + len = strncpy_from_user(name, name_user, MODULE_NAME_LEN); > + if (len == 0 || len == MODULE_NAME_LEN) > + return -ENOENT; > + if (len < 0) > + return len; This looks correct to me. The new code not only returns the correct errors indicated in delete_module(2) but also checks for the case user passes an empty string and the case where NUL char is not found when copying (with len == MODULE_NAME_LEN) as well as it's using the correct length (MODULE_NAME_LEN) for copying. Reviewed-by: Daniel Gomez