From: Jiri Slaby <jirislaby@kernel.org>
To: Romain Perier <romain.perier@gmail.com>,
Kees Cook <keescook@chromium.org>,
kernel-hardening@lists.openwall.com,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 17/20] vt: Manual replacement of the deprecated strlcpy() with return values
Date: Fri, 26 Feb 2021 10:49:02 +0100 [thread overview]
Message-ID: <a9f26339-c366-40c4-1cd6-c7ae1838e2b6@kernel.org> (raw)
In-Reply-To: <20210222151231.22572-18-romain.perier@gmail.com>
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.
"length" and it's NUL, not NULL in this case.
> 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
s/that/which/ ?
"handles"
"value"
> by the corresponding strscpy calls with new handling of the return
> values (as it is quite different between the two functions).
Sorry, I have hard times understand the whole sentence. Could you
rephrase a bit?
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
>
> Signed-off-by: Romain Perier <romain.perier@gmail.com>
> ---
> drivers/tty/vt/keyboard.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
> index 77638629c562..5e20c6c307e0 100644
> --- a/drivers/tty/vt/keyboard.c
> +++ b/drivers/tty/vt/keyboard.c
> @@ -2067,9 +2067,12 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
> return -ENOMEM;
>
> spin_lock_irqsave(&func_buf_lock, flags);
> - len = strlcpy(kbs, func_table[kb_func] ? : "", len);
> + len = strscpy(kbs, func_table[kb_func] ? : "", len);
func_table[kb_func] is NUL-terminated and kbs is of length len anyway,
so this is only cosmetical.
> spin_unlock_irqrestore(&func_buf_lock, flags);
>
> + if (len == -E2BIG)
> + return -E2BIG;
> +
This can never happen, right?
> ret = copy_to_user(user_kdgkb->kb_string, kbs, len + 1) ?
> -EFAULT : 0;
>
>
thanks,
--
js
next prev parent reply other threads:[~2021-02-26 9:50 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 15:12 [PATCH 00/20] Manual replacement of all strlcpy in favor of strscpy Romain Perier
2021-02-22 15:12 ` [PATCH 01/20] cgroup: Manual replacement of the deprecated strlcpy() with return values Romain Perier
2021-02-23 16:13 ` Michal Koutný
2021-02-22 15:12 ` [PATCH 02/20] crypto: " Romain Perier
2021-03-04 4:37 ` Herbert Xu
2021-02-22 15:12 ` [PATCH 03/20] devlink: " Romain Perier
2021-02-23 0:56 ` Jakub Kicinski
2021-02-22 15:12 ` [PATCH 04/20] dma-buf: " Romain Perier
2021-02-22 15:12 ` [PATCH 05/20] kobject: " Romain Perier
2021-02-22 15:12 ` [PATCH 06/20] ima: " Romain Perier
2021-03-02 13:29 ` Mimi Zohar
2021-02-22 15:12 ` [PATCH 07/20] SUNRPC: " Romain Perier
2021-03-01 18:25 ` Chuck Lever
2021-02-22 15:12 ` [PATCH 08/20] kernfs: " Romain Perier
2021-02-22 15:12 ` [PATCH 09/20] m68k/atari: " Romain Perier
2021-02-22 15:12 ` [PATCH 10/20] module: " Romain Perier
2021-02-22 15:12 ` [PATCH 11/20] hwmon: " Romain Perier
2021-02-22 15:46 ` Guenter Roeck
2021-02-28 11:50 ` Joe Perches
2021-02-22 15:12 ` [PATCH 12/20] s390/hmcdrv: " Romain Perier
2021-02-22 15:12 ` [PATCH 13/20] scsi: zfcp: " Romain Perier
2021-02-22 16:04 ` Benjamin Block
2021-02-22 15:12 ` [PATCH 14/20] target: " Romain Perier
2021-02-22 16:00 ` Bodo Stroesser
2021-02-22 18:09 ` kernel test robot
2021-02-22 15:12 ` [PATCH 15/20] ALSA: usb-audio: " Romain Perier
2021-02-22 15:39 ` Takashi Iwai
2021-02-22 15:12 ` [PATCH 16/20] tracing/probe: " Romain Perier
2021-02-22 17:49 ` Steven Rostedt
2021-02-22 15:12 ` [PATCH 17/20] vt: " Romain Perier
2021-02-26 9:49 ` Jiri Slaby [this message]
2021-02-22 15:12 ` [PATCH 18/20] usb: gadget: f_midi: " Romain Perier
2021-02-22 15:12 ` [PATCH 19/20] usbip: usbip_host: " Romain Perier
2021-02-22 16:21 ` Shuah Khan
2021-02-28 9:03 ` Sergei Shtylyov
2021-02-22 15:12 ` [PATCH 20/20] s390/watchdog: " Romain Perier
2021-02-22 15:55 ` Guenter Roeck
2021-02-22 16:36 ` [PATCH 00/20] Manual replacement of all strlcpy in favor of strscpy Shuah Khan
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