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[188.193.20.102]) by smtp.gmail.com with ESMTPSA id v12sm1792101edx.90.2021.02.22.08.00.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 22 Feb 2021 08:00:31 -0800 (PST) Subject: Re: [PATCH 14/20] target: Manual replacement of the deprecated strlcpy() with return values To: Romain Perier , Kees Cook , kernel-hardening@lists.openwall.com, "Martin K. Petersen" Cc: linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210222151231.22572-1-romain.perier@gmail.com> <20210222151231.22572-15-romain.perier@gmail.com> From: Bodo Stroesser Message-ID: Date: Mon, 22 Feb 2021 17:00:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210222151231.22572-15-romain.perier@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22.02.21 16:12, Romain Perier wrote: > The strlcpy() reads the entire source buffer first, it is dangerous if > the source buffer lenght is unbounded or possibility non NULL-terminated. > It can lead to linear read overflows, crashes, etc... > > As recommended in the deprecated interfaces [1], it should be replaced > by strscpy. > > This commit replaces all calls to strlcpy that handle the return values > by the corresponding strscpy calls with new handling of the return > values (as it is quite different between the two functions). > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy > > Signed-off-by: Romain Perier > --- > drivers/target/target_core_configfs.c | 33 +++++++++------------------------ > 1 file changed, 9 insertions(+), 24 deletions(-) > > diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c > index f04352285155..676215cd8847 100644 > --- a/drivers/target/target_core_configfs.c > +++ b/drivers/target/target_core_configfs.c > @@ -1325,16 +1325,11 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item, > /* +2 to allow for a trailing (stripped) '\n' and null-terminator */ > unsigned char buf[INQUIRY_VENDOR_LEN + 2]; > char *stripped = NULL; > - size_t len; > + ssize_t len; > ssize_t ret; > > - len = strlcpy(buf, page, sizeof(buf)); > - if (len < sizeof(buf)) { > - /* Strip any newline added from userspace. */ > - stripped = strstrip(buf); > - len = strlen(stripped); > - } > - if (len > INQUIRY_VENDOR_LEN) { > + len = strscpy(buf, page, sizeof(buf)); > + if (len == -E2BIG) { > pr_err("Emulated T10 Vendor Identification exceeds" > " INQUIRY_VENDOR_LEN: " __stringify(INQUIRY_VENDOR_LEN) > "\n"); > @@ -1381,16 +1376,11 @@ static ssize_t target_wwn_product_id_store(struct config_item *item, > /* +2 to allow for a trailing (stripped) '\n' and null-terminator */ > unsigned char buf[INQUIRY_MODEL_LEN + 2]; > char *stripped = NULL; > - size_t len; > + ssize_t len; > ssize_t ret; > > - len = strlcpy(buf, page, sizeof(buf)); > - if (len < sizeof(buf)) { > - /* Strip any newline added from userspace. */ > - stripped = strstrip(buf); > - len = strlen(stripped); > - } > - if (len > INQUIRY_MODEL_LEN) { > + len = strscpy(buf, page, sizeof(buf)); > + if (len == -E2BIG) { > pr_err("Emulated T10 Vendor exceeds INQUIRY_MODEL_LEN: " > __stringify(INQUIRY_MODEL_LEN) > "\n"); > @@ -1437,16 +1427,11 @@ static ssize_t target_wwn_revision_store(struct config_item *item, > /* +2 to allow for a trailing (stripped) '\n' and null-terminator */ > unsigned char buf[INQUIRY_REVISION_LEN + 2]; > char *stripped = NULL; > - size_t len; > + ssize_t len; > ssize_t ret; > > - len = strlcpy(buf, page, sizeof(buf)); > - if (len < sizeof(buf)) { > - /* Strip any newline added from userspace. */ > - stripped = strstrip(buf); > - len = strlen(stripped); > - } > - if (len > INQUIRY_REVISION_LEN) { > + len = strscpy(buf, page, sizeof(buf)); > + if (len == -E2BIG) { > pr_err("Emulated T10 Revision exceeds INQUIRY_REVISION_LEN: " > __stringify(INQUIRY_REVISION_LEN) > "\n"); > AFAICS, you are not only replacing strlcpy with strscpy, but also remove stripping of possible trailing '\n', and remove the necessary length check of the remaining string. -Bodo