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Message-ID: <032a2332-7acb-4d56-93bd-0ff9272290fa@embeddedor.com>
Date: Wed, 7 Feb 2024 11:36:31 -0600
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Kees Cook <keescook@...omium.org>, Brian Norris <briannorris@...omium.org>
Cc: Kalle Valo <kvalo@...nel.org>, Dmitry Antipov <dmantipov@...dex.ru>,
Johannes Berg <johannes.berg@...el.com>, zuoqilin <zuoqilin@...ong.com>,
Ruan Jinjie <ruanjinjie@...wei.com>, Thomas Gleixner <tglx@...utronix.de>,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
"Gustavo A . R . Silva" <gustavoars@...nel.org>,
linux-wireless@...r.kernel.org, Dan Carpenter <error27@...il.com>,
Francesco Dolcini <francesco.dolcini@...adex.com>,
David Lin <yu-hao.lin@....com>, Lukas Wunner <lukas@...ner.de>,
Simon Horman <horms@...nel.org>, linux-kernel@...r.kernel.org,
linux-hardening@...r.kernel.org
Subject: Re: [PATCH v3] wifi: mwifiex: Refactor 1-element array into flexible
array in struct mwifiex_ie_types_chan_list_param_set
On 2/7/24 04:30, Kees Cook wrote:
> struct mwifiex_ie_types_chan_list_param_set::chan_scan_param is treated
> as a flexible array, so convert it into one so that it doesn't trip
> the array bounds sanitizer[1]. Only a few places were using sizeof()
> on the whole struct, so adjust those to follow the calculation pattern
> to avoid including the trailing single element.
>
> Examining binary output differences doesn't appear to show any literal
> size values changing, though it is obfuscated a bit by the compiler
> adjusting register usage and stack spill slots, etc.
>
> Link: https://github.com/KSPP/linux/issues/51 [1]
> Cc: Brian Norris <briannorris@...omium.org>
> Cc: Kalle Valo <kvalo@...nel.org>
> Cc: Dmitry Antipov <dmantipov@...dex.ru>
> Cc: Johannes Berg <johannes.berg@...el.com>
> Cc: zuoqilin <zuoqilin@...ong.com>
> Cc: Ruan Jinjie <ruanjinjie@...wei.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> Cc: Gustavo A. R. Silva <gustavoars@...nel.org>
> Cc: linux-wireless@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>
TLV and one-element arrays are always tricky to transform (into flex arrays),
but (unless I'm missing something that the maintainers might point out) this
looks good to me.
Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>
Thanks!
--
Gustavo
> ---
> v3: catch two more cases of changed sizeof (gustavo)
> v2: https://lore.kernel.org/linux-hardening/20240206183857.it.362-kees@kernel.org/
> v1: https://lore.kernel.org/linux-hardening/20240206163501.work.158-kees@kernel.org/
> ---
> drivers/net/wireless/marvell/mwifiex/11n.c | 12 +++++-------
> drivers/net/wireless/marvell/mwifiex/fw.h | 2 +-
> drivers/net/wireless/marvell/mwifiex/scan.c | 14 ++++++--------
> 3 files changed, 12 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/net/wireless/marvell/mwifiex/11n.c b/drivers/net/wireless/marvell/mwifiex/11n.c
> index 90e401100898..c0c635e74bc5 100644
> --- a/drivers/net/wireless/marvell/mwifiex/11n.c
> +++ b/drivers/net/wireless/marvell/mwifiex/11n.c
> @@ -392,12 +392,10 @@ mwifiex_cmd_append_11n_tlv(struct mwifiex_private *priv,
>
> chan_list =
> (struct mwifiex_ie_types_chan_list_param_set *) *buffer;
> - memset(chan_list, 0,
> - sizeof(struct mwifiex_ie_types_chan_list_param_set));
> + memset(chan_list, 0, struct_size(chan_list, chan_scan_param, 1));
> chan_list->header.type = cpu_to_le16(TLV_TYPE_CHANLIST);
> - chan_list->header.len = cpu_to_le16(
> - sizeof(struct mwifiex_ie_types_chan_list_param_set) -
> - sizeof(struct mwifiex_ie_types_header));
> + chan_list->header.len =
> + cpu_to_le16(sizeof(struct mwifiex_chan_scan_param_set));
> chan_list->chan_scan_param[0].chan_number =
> bss_desc->bcn_ht_oper->primary_chan;
> chan_list->chan_scan_param[0].radio_type =
> @@ -411,8 +409,8 @@ mwifiex_cmd_append_11n_tlv(struct mwifiex_private *priv,
> (bss_desc->bcn_ht_oper->ht_param &
> IEEE80211_HT_PARAM_CHA_SEC_OFFSET));
>
> - *buffer += sizeof(struct mwifiex_ie_types_chan_list_param_set);
> - ret_len += sizeof(struct mwifiex_ie_types_chan_list_param_set);
> + *buffer += struct_size(chan_list, chan_scan_param, 1);
> + ret_len += struct_size(chan_list, chan_scan_param, 1);
> }
>
> if (bss_desc->bcn_bss_co_2040) {
> diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h
> index 62f3c9a52a1d..3adc447b715f 100644
> --- a/drivers/net/wireless/marvell/mwifiex/fw.h
> +++ b/drivers/net/wireless/marvell/mwifiex/fw.h
> @@ -770,7 +770,7 @@ struct mwifiex_chan_scan_param_set {
>
> struct mwifiex_ie_types_chan_list_param_set {
> struct mwifiex_ie_types_header header;
> - struct mwifiex_chan_scan_param_set chan_scan_param[1];
> + struct mwifiex_chan_scan_param_set chan_scan_param[];
> } __packed;
>
> struct mwifiex_ie_types_rxba_sync {
> diff --git a/drivers/net/wireless/marvell/mwifiex/scan.c b/drivers/net/wireless/marvell/mwifiex/scan.c
> index a2ddac363b10..0326b121747c 100644
> --- a/drivers/net/wireless/marvell/mwifiex/scan.c
> +++ b/drivers/net/wireless/marvell/mwifiex/scan.c
> @@ -664,15 +664,14 @@ mwifiex_scan_channel_list(struct mwifiex_private *priv,
>
> /* Copy the current channel TLV to the command being
> prepared */
> - memcpy(chan_tlv_out->chan_scan_param + tlv_idx,
> + memcpy(&chan_tlv_out->chan_scan_param[tlv_idx],
> tmp_chan_list,
> - sizeof(chan_tlv_out->chan_scan_param));
> + sizeof(*chan_tlv_out->chan_scan_param));
>
> /* Increment the TLV header length by the size
> appended */
> le16_unaligned_add_cpu(&chan_tlv_out->header.len,
> - sizeof(
> - chan_tlv_out->chan_scan_param));
> + sizeof(*chan_tlv_out->chan_scan_param));
>
> /*
> * The tlv buffer length is set to the number of bytes
> @@ -2369,12 +2368,11 @@ int mwifiex_cmd_802_11_bg_scan_config(struct mwifiex_private *priv,
> chan_idx < MWIFIEX_BG_SCAN_CHAN_MAX &&
> bgscan_cfg_in->chan_list[chan_idx].chan_number;
> chan_idx++) {
> - temp_chan = chan_list_tlv->chan_scan_param + chan_idx;
> + temp_chan = &chan_list_tlv->chan_scan_param[chan_idx];
>
> /* Increment the TLV header length by size appended */
> le16_unaligned_add_cpu(&chan_list_tlv->header.len,
> - sizeof(
> - chan_list_tlv->chan_scan_param));
> + sizeof(*chan_list_tlv->chan_scan_param));
>
> temp_chan->chan_number =
> bgscan_cfg_in->chan_list[chan_idx].chan_number;
> @@ -2413,7 +2411,7 @@ int mwifiex_cmd_802_11_bg_scan_config(struct mwifiex_private *priv,
> chan_scan_param);
> le16_unaligned_add_cpu(&chan_list_tlv->header.len,
> chan_num *
> - sizeof(chan_list_tlv->chan_scan_param[0]));
> + sizeof(*chan_list_tlv->chan_scan_param));
> }
>
> tlv_pos += (sizeof(chan_list_tlv->header)
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