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

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

[Romain Perier]

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

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[PATCH 04/20] dma-buf: Manual replacement of the deprecated strlcpy() with return values

[Romain Perier]

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/dma-buf/dma-buf.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index f264b70c383e..515192f2f404 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -42,12 +42,12 @@ static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
 {
 	struct dma_buf *dmabuf;
 	char name[DMA_BUF_NAME_LEN];
-	size_t ret = 0;
+	ssize_t ret = 0;
 
 	dmabuf = dentry->d_fsdata;
 	spin_lock(&dmabuf->name_lock);
 	if (dmabuf->name)
-		ret = strlcpy(name, dmabuf->name, DMA_BUF_NAME_LEN);
+		ret = strscpy(name, dmabuf->name, DMA_BUF_NAME_LEN);
 	spin_unlock(&dmabuf->name_lock);
 
 	return dynamic_dname(dentry, buffer, buflen, "/%s:%s",

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

[Shuah Khan]

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

[Romain Perier]

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Le lun. 22 févr. 2021 à 17:36, Shuah Khan <skhan@linuxfoundation.org> a
écrit :

>
> 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,

Initially, what we planned with Kees is to firstly replace all calls with
error handling codes (like this series does),
and then replace all other simple calls (without error handling). However,
we can also start a discussion about this topic, all suggestions are
welcome.

I am not sure that it does make sense to check all returns code in all
cases (for example in arch/alpha/kernel/setup.c, there are a ton of other
examples in the kernel). But a general review (as you suggest), would make
sense.

Regards,
Romain

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