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[82.28.105.188]) by smtp.gmail.com with ESMTPSA id b187sm5244540wmb.8.2020.09.11.09.09.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Sep 2020 09:09:21 -0700 (PDT) Subject: Re: [PATCH] security: keys: Use kvfree_sensitive in a few places To: efremov@linux.com Cc: David Howells , Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org References: <20200911114400.82207-1-alex.dewar90@gmail.com> From: Alex Dewar Message-ID: Date: Fri, 11 Sep 2020 17:09:20 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-09-11 17:05, Denis Efremov wrote: > Hi, > > same patch > > https://lkml.org/lkml/2020/8/27/168 > > Thanks, > Denis Ah ok. Sorry for the noise! > > On 9/11/20 2:44 PM, Alex Dewar wrote: >> In big_key.c, there are a few places where memzero_explicit + kvfree is >> used. It is better to use kvfree_sensitive instead, which is more >> readable and also prevents the compiler from eliding the call to >> memzero_explicit. Fix this. >> >> Signed-off-by: Alex Dewar >> --- >> security/keys/big_key.c | 9 +++------ >> 1 file changed, 3 insertions(+), 6 deletions(-) >> >> diff --git a/security/keys/big_key.c b/security/keys/big_key.c >> index 691347dea3c1..d17e5f09eeb8 100644 >> --- a/security/keys/big_key.c >> +++ b/security/keys/big_key.c >> @@ -121,8 +121,7 @@ int big_key_preparse(struct key_preparsed_payload *prep) >> *path = file->f_path; >> path_get(path); >> fput(file); >> - memzero_explicit(buf, enclen); >> - kvfree(buf); >> + kvfree_sensitive(buf, enclen); >> } else { >> /* Just store the data in a buffer */ >> void *data = kmalloc(datalen, GFP_KERNEL); >> @@ -140,8 +139,7 @@ int big_key_preparse(struct key_preparsed_payload *prep) >> err_enckey: >> kfree_sensitive(enckey); >> error: >> - memzero_explicit(buf, enclen); >> - kvfree(buf); >> + kvfree_sensitive(buf, enclen); >> return ret; >> } >> >> @@ -273,8 +271,7 @@ long big_key_read(const struct key *key, char *buffer, size_t buflen) >> err_fput: >> fput(file); >> error: >> - memzero_explicit(buf, enclen); >> - kvfree(buf); >> + kvfree_sensitive(buf, enclen); >> } else { >> ret = datalen; >> memcpy(buffer, key->payload.data[big_key_data], datalen); >>