On 2018/7/2 4:57, Guenter Roeck wrote:
> gcc 8.1.0 complains:
>
> fs/f2fs/namei.c: In function 'f2fs_update_extension_list':
> fs/f2fs/namei.c:257:3: warning:
> 'strncpy' output truncated before terminating nul copying
> as many bytes from a string as its length
> fs/f2fs/namei.c:249:3: warning:
> 'strncpy' output truncated before terminating nul copying
> as many bytes from a string as its length
>
> Using strncpy() is indeed less than perfect since the length of data to
> be copied has already been determined with strlen(). Replace strncpy()
> with memcpy() to address the warning and optimize the code a little.
>
> Signed-off-by: Guenter Roeck <li...@roeck-us.net>
> ---
> fs/f2fs/namei.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> index 231b7f3ea7d3..e75607544f7c 100644
> --- a/fs/f2fs/namei.c
> +++ b/fs/f2fs/namei.c
> @@ -246,7 +246,7 @@ int f2fs_update_extension_list(struct f2fs_sb_info *sbi,
> const char *name,
> return -EINVAL;
>
> if (hot) {
> - strncpy(extlist[count], name, strlen(name));
> + memcpy(extlist[count], name, strlen(name));
How about replacing with strcpy(extlist[count], name)? Because name length has
already been checked before f2fs_update_extension_list, it should be valid, and
will not cause overflow during copying.
Thanks,
> sbi->raw_super->hot_ext_count = hot_count + 1;
> } else {
> char buf[F2FS_MAX_EXTENSION][F2FS_EXTENSION_LEN];
> @@ -254,7 +254,7 @@ int f2fs_update_extension_list(struct f2fs_sb_info *sbi,
> const char *name,
> memcpy(buf, &extlist[cold_count],
> F2FS_EXTENSION_LEN * hot_count);
> memset(extlist[cold_count], 0, F2FS_EXTENSION_LEN);
> - strncpy(extlist[cold_count], name, strlen(name));
> + memcpy(extlist[cold_count], name, strlen(name));
> memcpy(&extlist[cold_count + 1], buf,
> F2FS_EXTENSION_LEN * hot_count);
> sbi->raw_super->extension_count = cpu_to_le32(cold_count + 1);
>
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