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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 8B8AEC4338F for ; Tue, 24 Aug 2021 17:16:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73C04610FD for ; Tue, 24 Aug 2021 17:16:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239396AbhHXRRf (ORCPT ); Tue, 24 Aug 2021 13:17:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:52374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240176AbhHXRO0 (ORCPT ); Tue, 24 Aug 2021 13:14:26 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CD78F61A7A; Tue, 24 Aug 2021 17:01:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629824500; bh=/JHi0V3cli/t8sdZnMZ9wI7O5zk3Oa0nGm1mPlNynys=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PLPFeZ3Xm6zEjIyPEftG3ZxNzu9IdkPDgJ9+X+NvcsOQ4Ll5uTahLyx7gqsE4uj7C uLVdVI5bIrr5ByJaJ8nJFM1vyIOvC+oSW4gU8Cty2g67hKColDNGWID93mDfzMb3Nf MYVxjDt1bIq3OXwZUcU/Iwh/zTQ93RGtrkbR1aHTlPOB1Q5j5aIvQ0NXRr3eOT0PB3 7o+JyAameZwzq0Ih6Tk4t5srrU26lfXjvnyTbB3Hj5hgtXyeQSlW4JWtQcxl11eEU3 BIEPsKyMuNNCMbAzJeMEWxBED9BhxS4N2vWMAkNgX4FOdjEpWQKNOB+lrigY6RPbEa YLW/snDxvx1RQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Pavel Skripkin , syzbot+fc8cd9a673d4577fb2e4@syzkaller.appspotmail.com, Dan Carpenter , "David S . Miller" , Sasha Levin Subject: [PATCH 5.4 33/61] net: 6pack: fix slab-out-of-bounds in decode_data Date: Tue, 24 Aug 2021 13:00:38 -0400 Message-Id: <20210824170106.710221-34-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210824170106.710221-1-sashal@kernel.org> References: <20210824170106.710221-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.4.143-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-5.4.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 5.4.143-rc1 X-KernelTest-Deadline: 2021-08-26T17:01+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pavel Skripkin [ Upstream commit 19d1532a187669ce86d5a2696eb7275310070793 ] Syzbot reported slab-out-of bounds write in decode_data(). The problem was in missing validation checks. Syzbot's reproducer generated malicious input, which caused decode_data() to be called a lot in sixpack_decode(). Since rx_count_cooked is only 400 bytes and noone reported before, that 400 bytes is not enough, let's just check if input is malicious and complain about buffer overrun. Fail log: ================================================================== BUG: KASAN: slab-out-of-bounds in drivers/net/hamradio/6pack.c:843 Write of size 1 at addr ffff888087c5544e by task kworker/u4:0/7 CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.6.0-rc3-syzkaller #0 ... Workqueue: events_unbound flush_to_ldisc Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:641 __asan_report_store1_noabort+0x17/0x20 mm/kasan/generic_report.c:137 decode_data.part.0+0x23b/0x270 drivers/net/hamradio/6pack.c:843 decode_data drivers/net/hamradio/6pack.c:965 [inline] sixpack_decode drivers/net/hamradio/6pack.c:968 [inline] Reported-and-tested-by: syzbot+fc8cd9a673d4577fb2e4@syzkaller.appspotmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Pavel Skripkin Reviewed-by: Dan Carpenter Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/hamradio/6pack.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c index 71d6629e65c9..da13683d52d1 100644 --- a/drivers/net/hamradio/6pack.c +++ b/drivers/net/hamradio/6pack.c @@ -839,6 +839,12 @@ static void decode_data(struct sixpack *sp, unsigned char inbyte) return; } + if (sp->rx_count_cooked + 2 >= sizeof(sp->cooked_buf)) { + pr_err("6pack: cooked buffer overrun, data loss\n"); + sp->rx_count = 0; + return; + } + buf = sp->raw_buf; sp->cooked_buf[sp->rx_count_cooked++] = buf[0] | ((buf[1] << 2) & 0xc0); -- 2.30.2