diff options
| author | Justin Stitt <justinstitt@google.com> | 2023-07-27 21:53:24 +0000 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2023-07-29 13:53:39 +0200 |
| commit | 44900c3ee4a1047bf896ca4cd9a9c69000f04701 (patch) | |
| tree | 8654d6848e017c95f1e88a121f667c15d11365bf /sound/xen | |
| parent | 367ef1e1c4b65acc5d789ba00d20197eb66b62f4 (diff) | |
ALSA: xen-front: refactor deprecated strncpy
`strncpy` is deprecated for use on NUL-terminated destination strings [1].
A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on its destination buffer argument which is
_not_ always the case for `strncpy`!
It should be noted that, in this case, the destination buffer has a
length strictly greater than the source string. Moreover, the source
string is NUL-terminated (and so is the destination) which means there
was no real bug happening here. Nonetheless, this patch would get us one
step closer to eliminating the `strncpy` API in the kernel, as its use
is too ambiguous. We need to favor less ambiguous replacements such as:
strscpy, strscpy_pad, strtomem and strtomem_pad (amongst others).
Technically, my patch yields subtly different behavior. The original
implementation with `strncpy` would fill the entire destination buffer
with null bytes [3] while `strscpy` will leave the junk, uninitialized
bytes trailing after the _mandatory_ NUL-termination. So, if somehow
`pcm->name` or `card->driver/shortname/longname` require this
NUL-padding behavior then `strscpy_pad` should be used. My
interpretation, though, is that the aforementioned fields are just fine
as NUL-terminated strings. Please correct my assumptions if needed and
I'll send in a v2.
[1]: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
[2]: manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
[3]: https://linux.die.net/man/3/strncpy
Link: https://github.com/KSPP/linux/issues/90
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230727-sound-xen-v1-1-89dd161351f1@google.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/xen')
| -rw-r--r-- | sound/xen/xen_snd_front_alsa.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/sound/xen/xen_snd_front_alsa.c b/sound/xen/xen_snd_front_alsa.c index db917453a473..7a3dfce97c15 100644 --- a/sound/xen/xen_snd_front_alsa.c +++ b/sound/xen/xen_snd_front_alsa.c @@ -783,7 +783,7 @@ static int new_pcm_instance(struct xen_snd_front_card_info *card_info, pcm->info_flags = 0; /* we want to handle all PCM operations in non-atomic context */ pcm->nonatomic = true; - strncpy(pcm->name, "Virtual card PCM", sizeof(pcm->name)); + strscpy(pcm->name, "Virtual card PCM", sizeof(pcm->name)); if (instance_cfg->num_streams_pb) snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, @@ -835,9 +835,9 @@ int xen_snd_front_alsa_init(struct xen_snd_front_info *front_info) goto fail; } - strncpy(card->driver, XENSND_DRIVER_NAME, sizeof(card->driver)); - strncpy(card->shortname, cfg->name_short, sizeof(card->shortname)); - strncpy(card->longname, cfg->name_long, sizeof(card->longname)); + strscpy(card->driver, XENSND_DRIVER_NAME, sizeof(card->driver)); + strscpy(card->shortname, cfg->name_short, sizeof(card->shortname)); + strscpy(card->longname, cfg->name_long, sizeof(card->longname)); ret = snd_card_register(card); if (ret < 0) |