[PATCH 00/20] Manual replacement of all strlcpy in favor of strscpy

strlcpy() copy a C-String into a sized buffer, the result is always a
valid NULL-terminated that fits in the buffer, howerver it has severals
issues. It reads the source buffer first, which is dangerous if it is non
NULL-terminated or if the corresponding buffer is unbounded. Its safe
replacement is strscpy(), as suggested in the deprecated interface [1].

We plan to make this contribution in two steps:
- Firsly all cases of strlcpy's return value are manually replaced by the
  corresponding calls of strscpy() with the new handling of the return
  value (as the return code is different in case of error).
- Then all other cases are automatically replaced by using coccinelle.

This series covers manual replacements.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy

Romain Perier (20):
  cgroup: Manual replacement of the deprecated strlcpy() with return
    values
  crypto: Manual replacement of the deprecated strlcpy() with return
    values
  devlink: Manual replacement of the deprecated strlcpy() with return
    values
  dma-buf: Manual replacement of the deprecated strlcpy() with return
    values
  kobject: Manual replacement of the deprecated strlcpy() with return
    values
  ima: Manual replacement of the deprecated strlcpy() with return values
  SUNRPC: Manual replacement of the deprecated strlcpy() with return
    values
  kernfs: Manual replacement of the deprecated strlcpy() with return
    values
  m68k/atari: Manual replacement of the deprecated strlcpy() with return
    values
  module: Manual replacement of the deprecated strlcpy() with return
    values
  hwmon: Manual replacement of the deprecated strlcpy() with return
    values
  s390/hmcdrv: Manual replacement of the deprecated strlcpy() with
    return values
  scsi: zfcp: Manual replacement of the deprecated strlcpy() with return
    values
  target: Manual replacement of the deprecated strlcpy() with return
    values
  ALSA: usb-audio: Manual replacement of the deprecated strlcpy() with
    return values
  tracing/probe: Manual replacement of the deprecated strlcpy() with
    return values
  vt: Manual replacement of the deprecated strlcpy() with return values
  usb: gadget: f_midi: Manual replacement of the deprecated strlcpy()
    with return values
  usbip: usbip_host: Manual replacement of the deprecated strlcpy() with
    return values
  s390/watchdog: Manual replacement of the deprecated strlcpy() with
    return values

 arch/m68k/emu/natfeat.c                 |  6 +--
 crypto/lrw.c                            |  6 +--
 crypto/xts.c                            |  6 +--
 drivers/dma-buf/dma-buf.c               |  4 +-
 drivers/hwmon/pmbus/max20730.c          | 66 +++++++++++++------------
 drivers/s390/char/diag_ftp.c            |  4 +-
 drivers/s390/char/sclp_ftp.c            |  6 +--
 drivers/s390/scsi/zfcp_fc.c             |  8 +--
 drivers/target/target_core_configfs.c   | 33 ++++---------
 drivers/tty/vt/keyboard.c               |  5 +-
 drivers/usb/gadget/function/f_midi.c    |  4 +-
 drivers/usb/gadget/function/f_printer.c |  8 +--
 drivers/usb/usbip/stub_main.c           |  6 +--
 drivers/watchdog/diag288_wdt.c          | 12 +++--
 fs/kernfs/dir.c                         | 27 +++++-----
 kernel/cgroup/cgroup.c                  |  2 +-
 kernel/module.c                         |  4 +-
 kernel/trace/trace_uprobe.c             | 11 ++---
 lib/kobject_uevent.c                    |  6 +--
 net/core/devlink.c                      |  6 +--
 net/sunrpc/clnt.c                       |  6 ++-
 security/integrity/ima/ima_policy.c     |  8 ++-
 sound/usb/card.c                        |  4 +-
 23 files changed, 129 insertions(+), 119 deletions(-)

-- 
2.20.1

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 <romain.perier@gmail.com>
---
 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");

On 22.02.21 16:12, Romain Perier wrote:

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

On 2/22/21 8:12 AM, Romain Perier wrote:

strlcpy() copy a C-String into a sized buffer, the result is always a
valid NULL-terminated that fits in the buffer, howerver it has severals
issues. It reads the source buffer first, which is dangerous if it is non
NULL-terminated or if the corresponding buffer is unbounded. Its safe
replacement is strscpy(), as suggested in the deprecated interface [1].

We plan to make this contribution in two steps:
- Firsly all cases of strlcpy's return value are manually replaced by the
   corresponding calls of strscpy() with the new handling of the return
   value (as the return code is different in case of error).
- Then all other cases are automatically replaced by using coccinelle.

Cool. A quick check shows me 1031 strscpy() calls with no return
checks. All or some of these probably need to be reviewed and add
return checks. Is this something that is in the plan to address as
part of this work?

thanks,
-- Shuah

Hi Romain,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on s390/features]
[also build test WARNING on cryptodev/master crypto/master driver-core/driver-core-testing linus/master v5.11 next-20210222]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Romain-Perier/Manual-replacement-of-all-strlcpy-in-favor-of-strscpy/20210222-232701
base:   https://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git features
config: x86_64-randconfig-s022-20210222 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-229-g60c1f270-dirty
        # https://github.com/0day-ci/linux/commit/8b76bc6bcdb6b3d4847d4c6298b53759acc0849a
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Romain-Perier/Manual-replacement-of-all-strlcpy-in-favor-of-strscpy/20210222-232701
        git checkout 8b76bc6bcdb6b3d4847d4c6298b53759acc0849a
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All warnings (new ones prefixed by >>):

   drivers/target/target_core_configfs.c: In function 'target_check_inquiry_data.constprop':

quoted

drivers/target/target_core_configfs.c:1293:8: warning: argument 1 null where non-null expected [-Wnonnull]

    1293 |  len = strlen(buf);
         |        ^~~~~~~~~~~
   In file included from include/linux/bitmap.h:9,
                    from include/linux/cpumask.h:12,
                    from arch/x86/include/asm/cpumask.h:5,
                    from arch/x86/include/asm/msr.h:11,
                    from arch/x86/include/asm/processor.h:22,
                    from arch/x86/include/asm/timex.h:5,
                    from include/linux/timex.h:65,
                    from include/linux/time32.h:13,
                    from include/linux/time.h:60,
                    from include/linux/stat.h:19,
                    from include/linux/module.h:13,
                    from drivers/target/target_core_configfs.c:15:
   include/linux/string.h:89:24: note: in a call to function 'strlen' declared here
      89 | extern __kernel_size_t strlen(const char *);
         |                        ^~~~~~


vim +1293 drivers/target/target_core_configfs.c

c66ac9db8d4ad9 Nicholas Bellinger 2010-12-17  1287  
0322913cab79e4 Alan Adamson       2019-03-01  1288  static ssize_t target_check_inquiry_data(char *buf)
0322913cab79e4 Alan Adamson       2019-03-01  1289  {
0322913cab79e4 Alan Adamson       2019-03-01  1290  	size_t len;
0322913cab79e4 Alan Adamson       2019-03-01  1291  	int i;
0322913cab79e4 Alan Adamson       2019-03-01  1292  
0322913cab79e4 Alan Adamson       2019-03-01 @1293  	len = strlen(buf);
0322913cab79e4 Alan Adamson       2019-03-01  1294  
0322913cab79e4 Alan Adamson       2019-03-01  1295  	/*
0322913cab79e4 Alan Adamson       2019-03-01  1296  	 * SPC 4.3.1:
0322913cab79e4 Alan Adamson       2019-03-01  1297  	 * ASCII data fields shall contain only ASCII printable characters
0322913cab79e4 Alan Adamson       2019-03-01  1298  	 * (i.e., code values 20h to 7Eh) and may be terminated with one or
0322913cab79e4 Alan Adamson       2019-03-01  1299  	 * more ASCII null (00h) characters.
0322913cab79e4 Alan Adamson       2019-03-01  1300  	 */
0322913cab79e4 Alan Adamson       2019-03-01  1301  	for (i = 0; i < len; i++) {
0322913cab79e4 Alan Adamson       2019-03-01  1302  		if (buf[i] < 0x20 || buf[i] > 0x7E) {
0322913cab79e4 Alan Adamson       2019-03-01  1303  			pr_err("Emulated T10 Inquiry Data contains non-ASCII-printable characters\n");
0322913cab79e4 Alan Adamson       2019-03-01  1304  			return -EINVAL;
0322913cab79e4 Alan Adamson       2019-03-01  1305  		}
0322913cab79e4 Alan Adamson       2019-03-01  1306  	}
0322913cab79e4 Alan Adamson       2019-03-01  1307  
0322913cab79e4 Alan Adamson       2019-03-01  1308  	return len;
0322913cab79e4 Alan Adamson       2019-03-01  1309  }
0322913cab79e4 Alan Adamson       2019-03-01  1310  

---
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