From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail115-69.sinamail.sina.com.cn (mail115-69.sinamail.sina.com.cn [218.30.115.69]) (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 1BFBC2E62B for ; Sat, 18 May 2024 11:41:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=218.30.115.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716032491; cv=none; b=e0gDZalqNaJCNueTf6P+KwKqYsf/Qtqf/gwIL2HWWg3jWkd5cYB/xUuK9LelbA7n3gcNOhKYlf07EOY2YdVUyB4UvKvRy+pTu6d/5AzPHyLJxtQzdpzU4AH2fPAEnPjCJdnrnngvclshk06SrRwyuWO/5Z8QBe7k9O/CCvShJfk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716032491; c=relaxed/simple; bh=FT9g0mVJkaULAbLCz6DFh6+4/pfYztHg6RKsLSGzaKc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=iNnppgZWLtKzzcwUtpKm7XWhW4U9/0zqwr1a5Uo7bbZCrIAyhpcalvJGU66v2hYtvwXDAzQ06lWqLNKQxvqOr5gM5DqXYtuk5Or94TNhmI9FdVntAaE6siBnYLnpAOv8i9sBcokQJgnxgmKZd8VcQNTJ6BW9muT5o/m4p9FIEvg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; arc=none smtp.client-ip=218.30.115.69 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([113.118.65.249]) by sina.com (10.75.12.45) with ESMTP id 664893DA000080FD; Sat, 18 May 2024 19:41:17 +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: 21449531457749 X-SMAIL-UIID: BA5C5DCC219A4AD89BC009DD1F383FB1-20240518-194117-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [v9fs?] KASAN: slab-use-after-free Read in p9_fid_destroy Date: Sat, 18 May 2024 19:41:05 +0800 Message-Id: <20240518114105.1730-1-hdanton@sina.com> In-Reply-To: <00000000000049897e0618a4b1ff@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 On Fri, 17 May 2024 04:31:28 -0700 > syzbot has found a reproducer for the following issue on: > > HEAD commit: ea5f6ad9ad96 Merge tag 'platform-drivers-x86-v6.10-1' of g.. > git tree: upstream > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11df3084980000 #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git ea5f6ad9ad96 --- x/net/9p/client.c +++ y/net/9p/client.c @@ -879,15 +879,19 @@ static void p9_fid_destroy(struct p9_fid { struct p9_client *clnt; unsigned long flags; + bool empty; p9_debug(P9_DEBUG_FID, "fid %d\n", fid->fid); trace_9p_fid_ref(fid, P9_FID_REF_DESTROY); clnt = fid->clnt; spin_lock_irqsave(&clnt->lock, flags); idr_remove(&clnt->fids, fid->fid); + empty = idr_is_empty(&clnt->fids) && clnt->status == Hung + 1; spin_unlock_irqrestore(&clnt->lock, flags); kfree(fid->rdir); kfree(fid); + if (empty) + kfree(clnt); } /* We also need to export tracepoint symbols for tracepoint_enabled() */ @@ -1057,6 +1061,8 @@ EXPORT_SYMBOL(p9_client_create); void p9_client_destroy(struct p9_client *clnt) { struct p9_fid *fid; + unsigned long flags; + bool empty; int id; p9_debug(P9_DEBUG_MUX, "clnt %p\n", clnt); @@ -1068,13 +1074,18 @@ void p9_client_destroy(struct p9_client idr_for_each_entry(&clnt->fids, fid, id) { pr_info("Found fid %d not clunked\n", fid->fid); - p9_fid_destroy(fid); } p9_tag_cleanup(clnt); kmem_cache_destroy(clnt->fcall_cache); - kfree(clnt); + spin_lock_irqsave(&clnt->lock, flags); + clnt->status = Hung + 1; + empty = idr_is_empty(&clnt->fids); + spin_unlock_irqrestore(&clnt->lock, flags); + + if (empty) + kfree(clnt); } EXPORT_SYMBOL(p9_client_destroy); --