mbox series

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

Message ID 20210222151231.22572-1-romain.perier@gmail.com
Headers show
Series Manual replacement of all strlcpy in favor of strscpy | expand

Message

Romain Perier Feb. 22, 2021, 3:12 p.m. UTC
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(-)

Comments

Shuah Khan Feb. 22, 2021, 4:36 p.m. UTC | #1
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
Sergei Shtylyov Feb. 28, 2021, 9:03 a.m. UTC | #2
Hello!

On 22.02.2021 18:12, 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.


    Length. Possibly?

> 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>

[...]

MBR, Sergei