Subject: Re: [PATCH] mwifiex: Fix memory corruption in dump_station

From: Kalle Valo <[email-masked]>
Date: Mon, 18 May 2020 12:19:07 +0000 (UTC)

Pali Rohár <[email-masked]> wrote:

> The mwifiex_cfg80211_dump_station() uses static variable for iterating
> over a linked list of all associated stations (when the driver is in UAP
> role). This has a race condition if .dump_station is called in parallel
> for multiple interfaces. This corruption can be triggered by registering
> multiple SSIDs and calling, in parallel for multiple interfaces
>     iw dev <iface> station dump
> 
> [16750.719775] Unable to handle kernel paging request at virtual address dead000000000110
> ...
> [16750.899173] Call trace:
> [16750.901696]  mwifiex_cfg80211_dump_station+0x94/0x100 [mwifiex]
> [16750.907824]  nl80211_dump_station+0xbc/0x278 [cfg80211]
> [16750.913160]  netlink_dump+0xe8/0x320
> [16750.916827]  netlink_recvmsg+0x1b4/0x338
> [16750.920861]  ____sys_recvmsg+0x7c/0x2b0
> [16750.924801]  ___sys_recvmsg+0x70/0x98
> [16750.928564]  __sys_recvmsg+0x58/0xa0
> [16750.932238]  __arm64_sys_recvmsg+0x28/0x30
> [16750.936453]  el0_svc_common.constprop.3+0x90/0x158
> [16750.941378]  do_el0_svc+0x74/0x90
> [16750.944784]  el0_sync_handler+0x12c/0x1a8
> [16750.948903]  el0_sync+0x114/0x140
> [16750.952312] Code: f9400003 f907f423 eb02007f 54fffd60 (b9401060)
> [16750.958583] ---[ end trace c8ad181c2f4b8576 ]---
> 
> This patch drops the use of the static iterator, and instead every time
> the function is called iterates to the idx-th position of the
> linked-list.
> 
> It would be better to convert the code not to use linked list for
> associated stations storage (since the chip has a limited number of
> associated stations anyway - it could just be an array). Such a change
> may be proposed in the future. In the meantime this patch can backported
> into stable kernels in this simple form.
> 
> Fixes: 8baca1a34d4c ("mwifiex: dump station support in uap mode")
> Signed-off-by: Pali Rohár <[email-masked]>
> Acked-by: Ganapathi Bhat <[email-masked]>

Patch applied to wireless-drivers-next.git, thanks.

3aa42bae9c4d mwifiex: Fix memory corruption in dump_station

-- 
https://patchwork.kernel.org/patch/11550701/

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