linux-hardening - Re: [PATCH v3 1/2] wifi: brcm80211: replace deprecated strncpy with strscpy

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Message-ID: <169868644429.1993746.5520695482478737730.kvalo@kernel.org>
Date: Mon, 30 Oct 2023 17:20:45 +0000 (UTC)
From: Kalle Valo <kvalo@...nel.org>
To: Justin Stitt <justinstitt@...gle.com>
Cc: Arend van Spriel <aspriel@...il.com>,
 Franky Lin <franky.lin@...adcom.com>,
 Hante Meuleman <hante.meuleman@...adcom.com>, linux-wireless@...r.kernel.org,
 brcm80211-dev-list.pdl@...adcom.com, SHA-cyfmac-dev-list@...ineon.com,
 linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
 Justin Stitt <justinstitt@...gle.com>
Subject: Re: [PATCH v3 1/2] wifi: brcm80211: replace deprecated strncpy with
 strscpy

Justin Stitt <justinstitt@...gle.com> wrote:

> Let's move away from using strncpy and instead favor a less ambiguous
> and more robust interface.
> 
> For ifp->ndev->name, we expect ifp->ndev->name to be NUL-terminated based
> on its use in format strings within core.c:
> 67 |       char *brcmf_ifname(struct brcmf_if *ifp)
> 68 |       {
> 69 |            if (!ifp)
> 70 |                    return "<if_null>";
> 71 |
> 72 |            if (ifp->ndev)
> 73 |                    return ifp->ndev->name;
> 74 |
> 75 |            return "<if_none>";
> 76 |       }
> ...
> 288 |       static netdev_tx_t brcmf_netdev_start_xmit(struct sk_buff *skb,
> 289 |                                              struct net_device *ndev) {
> ...
> 330 |       brcmf_dbg(INFO, "%s: insufficient headroom (%d)\n",
> 331 |                 brcmf_ifname(ifp), head_delta);
> ...
> 336 |       bphy_err(drvr, "%s: failed to expand headroom\n",
> 337 |                brcmf_ifname(ifp));
> 
> For di->name, we expect di->name to be NUL-terminated based on its usage
> with format strings:
> |       brcms_dbg_dma(di->core,
> |                     "%s: DMA64 tx doesn't have AE set\n",
> |                     di->name);
> 
> Looking at its allocation we can see that it is already zero-allocated
> which means NUL-padding is not required:
> |       di = kzalloc(sizeof(struct dma_info), GFP_ATOMIC);
> 
> For wlc->modulecb[i].name, we expect each name in wlc->modulecb to be
> NUL-terminated based on their usage with strcmp():
> |       if (!strcmp(wlc->modulecb[i].name, name) &&
> 
> NUL-padding is not required as wlc is zero-allocated in:
> brcms_c_attach_malloc() ->
> |       wlc = kzalloc(sizeof(struct brcms_c_info), GFP_ATOMIC);
> 
> For all these cases, a suitable replacement is `strscpy` due to the fact
> that it guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding.
> 
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>
> Reviewed-by: Kees Cook <keescook@...omium.org>

2 patches applied to wireless-next.git, thanks.

9d0d0a207040 wifi: brcm80211: replace deprecated strncpy with strscpy
a614f9579705 wifi: brcmsmac: replace deprecated strncpy with memcpy

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20231017-strncpy-drivers-net-wireless-broadcom-brcm80211-brcmfmac-cfg80211-c-v3-1-af780d74ae38@google.com/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches