Re: [syzbot] [wireless?] KASAN: slab-use-after-free Read in cmp_bss

[Hillf Danton <hdanton@sina.com>]

> Date: Mon, 11 Aug 2025 11:59:31 -0700	[thread overview]
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    c30a13538d9f Merge tag 'bpf-fixes' of git://git.kernel.org..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=17840842580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=e143c1cd9dadd720
> dashboard link: https://syzkaller.appspot.com/bug?extid=30754ca335e6fb7e3092
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1766fea2580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15e709a2580000

#syz test

--- x/net/wireless/scan.c
+++ y/net/wireless/scan.c
@@ -1904,19 +1904,6 @@ cfg80211_update_known_bss(struct cfg8021
 
 		if (known->pub.hidden_beacon_bss &&
 		    !list_empty(&known->hidden_list)) {
-			const struct cfg80211_bss_ies *f;
-
-			/* The known BSS struct is one of the probe
-			 * response members of a group, but we're
-			 * receiving a beacon (beacon_ies in the new
-			 * bss is used). This can only mean that the
-			 * AP changed its beacon from not having an
-			 * SSID to showing it, which is confusing so
-			 * drop this information.
-			 */
-
-			f = rcu_access_pointer(new->pub.beacon_ies);
-			kfree_rcu((struct cfg80211_bss_ies *)f, rcu_head);
 			return false;
 		}
 
--