linux-kernel - Re: [PATCH] wifi: mwifiex: Fix memcpy() field-spanning write warning in mwifiex_config

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1b2af606-ade7-4550-b1ba-a78202b257e5@quicinc.com>
Date: Tue, 17 Sep 2024 11:10:08 -0700
From: Jeff Johnson <quic_jjohnson@...cinc.com>
To: Alper Nebi Yasak <alpernebiyasak@...il.com>,
        <linux-wireless@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: David Lin <yu-hao.lin@....com>, Dmitry Antipov <dmantipov@...dex.ru>,
        Brian Norris <briannorris@...omium.org>, Kalle Valo <kvalo@...nel.org>,
        Francesco Dolcini <francesco@...cini.it>,
        Sascha Hauer
	<s.hauer@...gutronix.de>, Kees Cook <kees@...nel.org>,
        "Gustavo A . R .
 Silva" <gustavoars@...nel.org>,
        Andy Shevchenko
	<andriy.shevchenko@...ux.intel.com>,
        Johannes Berg <johannes.berg@...el.com>
Subject: Re: [PATCH] wifi: mwifiex: Fix memcpy() field-spanning write warning
 in mwifiex_config_scan()

On 9/17/2024 8:08 AM, Alper Nebi Yasak wrote:
> Replace one-element array with a flexible-array member in `struct
> mwifiex_ie_types_wildcard_ssid_params` to fix the following warning
> on a MT8173 Chromebook (mt8173-elm-hana):
> 
> [  356.775250] ------------[ cut here ]------------
> [  356.784543] memcpy: detected field-spanning write (size 6) of single field "wildcard_ssid_tlv->ssid" at drivers/net/wireless/marvell/mwifiex/scan.c:904 (size 1)
> [  356.813403] WARNING: CPU: 3 PID: 742 at drivers/net/wireless/marvell/mwifiex/scan.c:904 mwifiex_scan_networks+0x4fc/0xf28 [mwifiex]
> 
> The "(size 6)" above is exactly the length of the SSID of the network
> this device was connected to. The source of the warning looks like:
> 
>     ssid_len = user_scan_in->ssid_list[i].ssid_len;
>     [...]
>     memcpy(wildcard_ssid_tlv->ssid,
>            user_scan_in->ssid_list[i].ssid, ssid_len);
> 
> Also adjust a #define that uses sizeof() on this struct to keep the
> value same as before.
> 
> Signed-off-by: Alper Nebi Yasak <alpernebiyasak@...il.com>
> ---
> I found these relevant patches that modify other such arrays, where the
> second one removes a -1 from some sizeof() calculation:
> 
> https://lore.kernel.org/lkml/Y9xkECG3uTZ6T1dN@work/T/#u
> https://lore.kernel.org/lkml/ZsZa5xRcsLq9D+RX@elsanto/T/#u
> 
> So I think we need the +1 to keep things same. But it appears to work
> fine without it, so I'm not sure. Maybe it should've had a -1 before
> that I would remove with this?

I think the original code was incorrect and was allocating too much memory.
I do not think WILDCARD_SSID_TLV_MAX_SIZE requires modification.

> 
>  drivers/net/wireless/marvell/mwifiex/fw.h   | 2 +-
>  drivers/net/wireless/marvell/mwifiex/scan.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h
> index d03129d5d24e..4a96281792cc 100644
> --- a/drivers/net/wireless/marvell/mwifiex/fw.h
> +++ b/drivers/net/wireless/marvell/mwifiex/fw.h
> @@ -875,7 +875,7 @@ struct mwifiex_ietypes_chanstats {
>  struct mwifiex_ie_types_wildcard_ssid_params {
>  	struct mwifiex_ie_types_header header;
>  	u8 max_ssid_length;
> -	u8 ssid[1];
> +	u8 ssid[];
>  } __packed;
>  
>  #define TSF_DATA_SIZE            8
> diff --git a/drivers/net/wireless/marvell/mwifiex/scan.c b/drivers/net/wireless/marvell/mwifiex/scan.c
> index cab889af4c4a..50af78ee935b 100644
> --- a/drivers/net/wireless/marvell/mwifiex/scan.c
> +++ b/drivers/net/wireless/marvell/mwifiex/scan.c
> @@ -32,7 +32,7 @@
>  #define WILDCARD_SSID_TLV_MAX_SIZE  \
>  	(MWIFIEX_MAX_SSID_LIST_LENGTH *					\
>  		(sizeof(struct mwifiex_ie_types_wildcard_ssid_params)	\
> -			+ IEEE80211_MAX_SSID_LEN))
> +			+ IEEE80211_MAX_SSID_LEN + 1))
>  
>  /* Maximum memory needed for a mwifiex_scan_cmd_config with all TLVs at max */
>  #define MAX_SCAN_CFG_ALLOC (sizeof(struct mwifiex_scan_cmd_config)        \
> 
> base-commit: 4f3e012d4cfd1d9bf837870c961f462ca9f23ebe