[ldv-project] [PATCH 5.10 1/1] mac80211: fix a memory leak where sta_info is not freed

[Greg Kroah-Hartman]

On Tue, Aug 09, 2022 at 07:02:45PM +0300, Viacheslav Sablin wrote:
> From: Ahmed Zaki <anzaki at gmail.com>
> 
> commit 8f9dcc29566626f683843ccac6113a12208315ca upstream.
> 
> The following is from a system that went OOM due to a memory leak:
> 
> wlan0: Allocated STA 74:83:c2:64:0b:87
> wlan0: Allocated STA 74:83:c2:64:0b:87
> wlan0: IBSS finish 74:83:c2:64:0b:87 (---from ieee80211_ibss_add_sta)
> wlan0: Adding new IBSS station 74:83:c2:64:0b:87
> wlan0: moving STA 74:83:c2:64:0b:87 to state 2
> wlan0: moving STA 74:83:c2:64:0b:87 to state 3
> wlan0: Inserted STA 74:83:c2:64:0b:87
> wlan0: IBSS finish 74:83:c2:64:0b:87 (---from ieee80211_ibss_work)
> wlan0: Adding new IBSS station 74:83:c2:64:0b:87
> wlan0: moving STA 74:83:c2:64:0b:87 to state 2
> wlan0: moving STA 74:83:c2:64:0b:87 to state 3
> .
> .
> wlan0: expiring inactive not authorized STA 74:83:c2:64:0b:87
> wlan0: moving STA 74:83:c2:64:0b:87 to state 2
> wlan0: moving STA 74:83:c2:64:0b:87 to state 1
> wlan0: Removed STA 74:83:c2:64:0b:87
> wlan0: Destroyed STA 74:83:c2:64:0b:87
> 
> The ieee80211_ibss_finish_sta() is called twice on the same STA from 2
> different locations. On the second attempt, the allocated STA is not
> destroyed creating a kernel memory leak.
> 
> This is happening because sta_info_insert_finish() does not call
> sta_info_free() the second time when the STA already exists (returns
> -EEXIST). Note that the caller sta_info_insert_rcu() assumes STA is
> destroyed upon errors.
> 
> Same fix is applied to -ENOMEM.
> 
> Signed-off-by: Ahmed Zaki <anzaki at gmail.com>
> Link: https://lore.kernel.org/r/20211002145329.3125293-1-anzaki@gmail.com
> [change the error path label to use the existing code]
> Signed-off-by: Johannes Berg <johannes.berg at intel.com>
> Signed-off-by: Viacheslav Sablin <sablin at ispras.ru>
> ---
>  net/mac80211/sta_info.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

This is also needed in 5.15.y, so added there as well.  thanks,

greg k-h