[RFC PATCH] wifi: mac80211: Replace strncpy() with strscpy()

[RFC PATCH] wifi: mac80211: Replace strncpy() with strscpy()

[I Hsin Cheng]

The name of vif which is "vif_name" should be NULL-terminated to be a
valid string, however "strncpy()" doesn't guarantee that. Replace it
with "strscpy()" to make sure the content within "vif_name" is
NULL-terminated.

Link: https://github.com/KSPP/linux/issues/90
Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
---
 net/mac80211/trace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac80211/trace.h b/net/mac80211/trace.h
index 72fad8ea8bb9..37f5b1c87709 100644
--- a/net/mac80211/trace.h
+++ b/net/mac80211/trace.h
@@ -1725,7 +1725,7 @@ TRACE_EVENT(drv_switch_vif_chanctx,
 				SWITCH_ENTRY_ASSIGN(vif.vif_type, vif->type);
 				SWITCH_ENTRY_ASSIGN(vif.p2p, vif->p2p);
 				SWITCH_ENTRY_ASSIGN(link_id, link_conf->link_id);
-				strncpy(local_vifs[i].vif.vif_name,
+				strscpy(local_vifs[i].vif.vif_name,
 					sdata->name,
 					sizeof(local_vifs[i].vif.vif_name));
 				SWITCH_ENTRY_ASSIGN(old_chandef.control_freq,
-- 
2.43.0

Re: [RFC PATCH] wifi: mac80211: Replace strncpy() with strscpy()

[I Hsin Cheng]

On Thu, Mar 27, 2025 at 10:11:08PM +0800, I Hsin Cheng wrote:
> The name of vif which is "vif_name" should be NULL-terminated to be a
> valid string, however "strncpy()" doesn't guarantee that. Replace it
> with "strscpy()" to make sure the content within "vif_name" is
> NULL-terminated.
> 
> Link: https://github.com/KSPP/linux/issues/90
> Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
> ---
>  net/mac80211/trace.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/mac80211/trace.h b/net/mac80211/trace.h
> index 72fad8ea8bb9..37f5b1c87709 100644
> --- a/net/mac80211/trace.h
> +++ b/net/mac80211/trace.h
> @@ -1725,7 +1725,7 @@ TRACE_EVENT(drv_switch_vif_chanctx,
>  				SWITCH_ENTRY_ASSIGN(vif.vif_type, vif->type);
>  				SWITCH_ENTRY_ASSIGN(vif.p2p, vif->p2p);
>  				SWITCH_ENTRY_ASSIGN(link_id, link_conf->link_id);
> -				strncpy(local_vifs[i].vif.vif_name,
> +				strscpy(local_vifs[i].vif.vif_name,
>  					sdata->name,
>  					sizeof(local_vifs[i].vif.vif_name));
>  				SWITCH_ENTRY_ASSIGN(old_chandef.control_freq,
> -- 
> 2.43.0
>

> The name of vif which is "vif_name" should be NULL-terminated to be a
Or maybe it should be trailing NULL-padding when sources is shorter, if
it's the case we should consider strscpy_pad() or other alternatives.

Let me know if there's any mistakes or tests I can help to validate,
thanks!

Best regards,
I Hsin Cheng

Re: [RFC PATCH] wifi: mac80211: Replace strncpy() with strscpy()

[Johannes Berg]

On Thu, 2025-03-27 at 22:11 +0800, I Hsin Cheng wrote:
> The name of vif which is "vif_name" should be NULL-terminated to be a
> valid string

And why should it be a "valid string"? This is just a buffer here in the
trace code. We don't even (and cannot) suggest how to print this, so I
think the userspace tool that does will just need to be careful, as with
anything else. Don't see any issue here.

johannes