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SubjectRe: [PATCH 3.16 62/63] mwifiex: fix possible heap overflow in mwifiex_process_country_ie()
Hi Ben,

On Wed, Jan 08, 2020 at 07:44:00PM +0000, Ben Hutchings wrote:
> 3.16.81-rc1 review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Ganapathi Bhat <gbhat@marvell.com>
>
> commit 3d94a4a8373bf5f45cf5f939e88b8354dbf2311b upstream.
>
> mwifiex_process_country_ie() function parse elements of bss
> descriptor in beacon packet. When processing WLAN_EID_COUNTRY
> element, there is no upper limit check for country_ie_len before
> calling memcpy. The destination buffer domain_info->triplet is an
> array of length MWIFIEX_MAX_TRIPLET_802_11D(83). The remote
> attacker can build a fake AP with the same ssid as real AP, and
> send malicous beacon packet with long WLAN_EID_COUNTRY elemen
> (country_ie_len > 83). Attacker can force STA connect to fake AP
> on a different channel. When the victim STA connects to fake AP,
> will trigger the heap buffer overflow. Fix this by checking for
> length and if found invalid, don not connect to the AP.
>
> This fix addresses CVE-2019-14895.
>
> Reported-by: huangwen <huangwenabc@gmail.com>
> Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
> [bwh: Backported to 3.16:
> - Use wiphy_dbg() instead of mwifiex_dbg()
> - Adjust filename]
> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> ---
> drivers/net/wireless/mwifiex/sta_ioctl.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> --- a/drivers/net/wireless/mwifiex/sta_ioctl.c
> +++ b/drivers/net/wireless/mwifiex/sta_ioctl.c
> @@ -223,6 +223,14 @@ static int mwifiex_process_country_ie(st
> "11D: skip setting domain info in FW\n");
> return 0;
> }
> +
> + if (country_ie_len >
> + (IEEE80211_COUNTRY_STRING_LEN + MWIFIEX_MAX_TRIPLET_802_11D)) {
> + wiphy_dbg(priv->wdev->wiphy,
> + "11D: country_ie_len overflow!, deauth AP\n");
> + return -EINVAL;
> + }
> +
> memcpy(priv->adapter->country_code, &country_ie[2], 2);
>
> domain_info->country_code[0] = country_ie[2];
> @@ -266,8 +274,9 @@ int mwifiex_bss_start(struct mwifiex_pri
> priv->scan_block = false;
>
> if (bss) {
> - if (adapter->region_code == 0x00)
> - mwifiex_process_country_ie(priv, bss);
> + if (adapter->region_code == 0x00 &&
> + mwifiex_process_country_ie(priv, bss))
> + return -EINVAL;
>
> /* Allocate and fill new bss descriptor */
> bss_desc = kzalloc(sizeof(struct mwifiex_bssdescriptor),
>

Brian Norris noted that this commit has unbalanced locking and
submitted a followup as per:

https://lkml.kernel.org/linux-wireless/20200106224212.189763-1-briannorris@chromium.org/T/#u
https://patchwork.kernel.org/patch/11320227/

Regards,
Salvatore

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