On 2020/12/16 下午12:20, Theodore Y. Ts'o wrote:
[Please note this e-mail is from an EXTERNAL e-mail address]
On Thu, Nov 12, 2020 at 05:33:24PM +0800, Kang Wenlin wrote:
From: Wenlin Kang <wenlin.kang@xxxxxxxxxxxxx>
The strncpy() function may create a unterminated string,
use strscpy_pad() instead.
This fixes the following warning:
fs/ext4/super.c: In function '__save_error_info':
fs/ext4/super.c:349:2: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
strncpy(es->s_last_error_func, func, sizeof(es->s_last_error_func));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/ext4/super.c:353:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
strncpy(es->s_first_error_func, func,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sizeof(es->s_first_error_func));
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
What compiler are you using? s_last_error_func is defined to not
necessarily be NUL terminated. So strscpy_pad() is not a proper
replacement for strncpy() in this use case.
My compiler is gcc 8.2.0, this is found in v4.18, and I see mainline
codes is
using the same code too, so sent this patch. But according to your
instructions,
I just re-check the code, with "__nonstring" attribute, it seems it has
fixed.
Thank for your explain.
From Documentation/process/deprecated:
If a caller is using non-NUL-terminated strings, strncpy() can
still be used, but destinations should be marked with the `__nonstring
<https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html>`_
attribute to avoid future compiler warnings.
s_{first,last}_error_func is properly annotated with __nonstring in
fs/ext4/ext4.h.
- Ted
--
Thanks,
Wenlin Kang
