From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from r3-22.sinamail.sina.com.cn (r3-22.sinamail.sina.com.cn [202.108.3.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 947C138B7B4 for ; Fri, 22 May 2026 21:23:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.108.3.22 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779485023; cv=none; b=fkeLbldkg6pstDUNWroYOWdyBs9hPom7LzY7B2yCFAi6M7TVSi/90Ji4wANcxsSoJ7Mjp06dipUmPdQPkIU7Wr7wRb1lzPnu4OI41p93NTiHXDYUlsBuGM9ROKygOE+uZ4lqxyEmf2nxdQhFZfZvrHQu07sRv4ZD5SbbMadCJL0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779485023; c=relaxed/simple; bh=JV6ZwP8PIoUd7k1DvJ8ATrkFfvwtXukZx/3JmDvpN8I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BBKndnVdgbq2wHN70p+qffEPJcvohF5o2Jz/0pvXFfpLpePWxsVo90E8F0HDGHgSq6Rt2GGA2Q3H9fLpP/LhzxEJR9WTP47SCvWTzc3C4upkeuOUBUTRP5x3E3X7J+dvJ4CEEEzsVZ+6YN7p607V4MQsA10MwOip7CTezJ7Xsxw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=s4LMURky; arc=none smtp.client-ip=202.108.3.22 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="s4LMURky" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1779485017; bh=Un922nc+IAjrQBYsAkHil3POySIVrDWo1b7HHHGHIXM=; h=From:Subject:Date:Message-ID; b=s4LMURkyxbpI2+T8BXZXP5B7VlDPk6SPh1wKyS8WARNjM15g/EP/a3tSh4AwK8TZ2 ejVsTumnSCKfExq+v88BItm2zrEvjKKfEY7wADMG67DHDRxZpRtPa5INnvo4me7vRk d11SFeT6XaEV0CMEt7ezITg61x14a/GLoWvaAK1w= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.62.144]) by sina.com (10.54.253.33) with ESMTP id 6A10C928000039B4; Fri, 23 May 2026 05:22:50 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 2845746684949 X-SMAIL-UIID: 6964ACAF61B2400A839CF40A530D24D3-20260523-052250-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [fs?] KASAN: slab-use-after-free Read in reverse_path_check_proc Date: Sat, 23 May 2026 05:22:37 +0800 Message-ID: <20260522212238.993-1-hdanton@sina.com> In-Reply-To: <6a10b30b.050a0220.19f61f.0003.GAE@google.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > Date: Fri, 22 May 2026 12:48:27 -0700 [thread overview] > Hello, > > syzbot found the following issue on: > > HEAD commit: 80dd246accce Add linux-next specific files for 20260518 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=113cba73980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=2a0b5969e136a632 > dashboard link: https://syzkaller.appspot.com/bug?extid=e70e1b6cba8714543f7c > compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14dc9fba580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10bffcc8580000 #syz test --- x/fs/eventpoll.c +++ y/fs/eventpoll.c @@ -456,14 +456,21 @@ static struct kmem_cache *pwq_cache __ro struct epitems_head { struct hlist_head epitems; struct epitems_head *next; + struct rcu_head rcu; }; static struct kmem_cache *ephead_cache __ro_after_init; +static void __free_ephead(struct rcu_head *r) +{ + struct epitems_head *head = container_of(r, struct epitems_head, rcu); + kmem_cache_free(ephead_cache, head); +} + static inline void free_ephead(struct epitems_head *head) { if (head) - kmem_cache_free(ephead_cache, head); + call_rcu(&head->rcu, __free_ephead); } static void list_file(struct file *file, struct ep_ctl_ctx *ctx) --