From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29E1CECDE4B for ; Thu, 8 Nov 2018 22:10:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E49892089F for ; Thu, 8 Nov 2018 22:10:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="bTJXbnRc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E49892089F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732948AbeKIHrl (ORCPT ); Fri, 9 Nov 2018 02:47:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:41520 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729415AbeKIHrk (ORCPT ); Fri, 9 Nov 2018 02:47:40 -0500 Received: from localhost (unknown [208.72.13.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A9D4E214DB; Thu, 8 Nov 2018 22:10:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541715007; bh=W513KvSHLy0RkfdR6FkAYep0ADwCiL36O+NVb39EkFg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bTJXbnRczk3a8xhEeNBNVn/Mh+H0lwNg1PtQK+/9hWvld2zGUKaRbTLRNNAeSBaca 748NajbtAooe8T/G/OvAEzvCCCxsVZovhX83cerSswRJZf71fLjdjf8Q0shDe9MyEE aRCDt+ig3pCqT2GoEsBwrRgiuGzmFuZOPVFKDVCI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+a95b989b2dde8e806af8@syzkaller.appspotmail.com, Eric Sandeen , David Howells Subject: [PATCH 4.18 08/34] fscache: Fix out of bound read in long cookie keys Date: Thu, 8 Nov 2018 13:52:37 -0800 Message-Id: <20181108215139.425688236@linuxfoundation.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181108215138.892971755@linuxfoundation.org> References: <20181108215138.892971755@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Sandeen commit fa520c47eaa15b9baa8ad66ac18da4a31679693b upstream. fscache_set_key() can incur an out-of-bounds read, reported by KASAN: BUG: KASAN: slab-out-of-bounds in fscache_alloc_cookie+0x5b3/0x680 [fscache] Read of size 4 at addr ffff88084ff056d4 by task mount.nfs/32615 and also reported by syzbot at https://lkml.org/lkml/2018/7/8/236 BUG: KASAN: slab-out-of-bounds in fscache_set_key fs/fscache/cookie.c:120 [inline] BUG: KASAN: slab-out-of-bounds in fscache_alloc_cookie+0x7a9/0x880 fs/fscache/cookie.c:171 Read of size 4 at addr ffff8801d3cc8bb4 by task syz-executor907/4466 This happens for any index_key_len which is not divisible by 4 and is larger than the size of the inline key, because the code allocates exactly index_key_len for the key buffer, but the hashing loop is stepping through it 4 bytes (u32) at a time in the buf[] array. Fix this by calculating how many u32 buffers we'll need by using DIV_ROUND_UP, and then using kcalloc() to allocate a precleared allocation buffer to hold the index_key, then using that same count as the hashing index limit. Fixes: ec0328e46d6e ("fscache: Maintain a catalogue of allocated cookies") Reported-by: syzbot+a95b989b2dde8e806af8@syzkaller.appspotmail.com Signed-off-by: Eric Sandeen Cc: stable Signed-off-by: David Howells Signed-off-by: Greg Kroah-Hartman --- fs/fscache/cookie.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/fs/fscache/cookie.c +++ b/fs/fscache/cookie.c @@ -70,7 +70,7 @@ void fscache_free_cookie(struct fscache_ } /* - * Set the index key in a cookie. The cookie struct has space for a 12-byte + * Set the index key in a cookie. The cookie struct has space for a 16-byte * key plus length and hash, but if that's not big enough, it's instead a * pointer to a buffer containing 3 bytes of hash, 1 byte of length and then * the key data. @@ -80,10 +80,13 @@ static int fscache_set_key(struct fscach { unsigned long long h; u32 *buf; + int bufs; int i; + bufs = DIV_ROUND_UP(index_key_len, sizeof(*buf)); + if (index_key_len > sizeof(cookie->inline_key)) { - buf = kzalloc(index_key_len, GFP_KERNEL); + buf = kcalloc(bufs, sizeof(*buf), GFP_KERNEL); if (!buf) return -ENOMEM; cookie->key = buf; @@ -98,7 +101,8 @@ static int fscache_set_key(struct fscach */ h = (unsigned long)cookie->parent; h += index_key_len + cookie->type; - for (i = 0; i < (index_key_len + sizeof(u32) - 1) / sizeof(u32); i++) + + for (i = 0; i < bufs; i++) h += buf[i]; cookie->key_hash = h ^ (h >> 32);