From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755563AbdDJRRO (ORCPT ); Mon, 10 Apr 2017 13:17:14 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36022 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755409AbdDJQuh (ORCPT ); Mon, 10 Apr 2017 12:50:37 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sami Tolvanen , Mike Snitzer Subject: [PATCH 4.10 023/110] dm verity fec: limit error correction recursion Date: Mon, 10 Apr 2017 18:42:14 +0200 Message-Id: <20170410164202.536447292@linuxfoundation.org> X-Mailer: git-send-email 2.12.2 In-Reply-To: <20170410164201.247583164@linuxfoundation.org> References: <20170410164201.247583164@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sami Tolvanen commit f1a880a93baaadb14c10a348fd199f1cdb6bcccd upstream. If the hash tree itself is sufficiently corrupt in addition to data blocks, it's possible for error correction to end up in a deep recursive loop, which eventually causes a kernel panic. This change limits the recursion to a reasonable level during a single I/O operation. Fixes: a739ff3f543a ("dm verity: add support for forward error correction") Signed-off-by: Sami Tolvanen Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-verity-fec.c | 12 +++++++++++- drivers/md/dm-verity-fec.h | 4 ++++ 2 files changed, 15 insertions(+), 1 deletion(-) --- a/drivers/md/dm-verity-fec.c +++ b/drivers/md/dm-verity-fec.c @@ -439,6 +439,13 @@ int verity_fec_decode(struct dm_verity * if (!verity_fec_is_enabled(v)) return -EOPNOTSUPP; + if (fio->level >= DM_VERITY_FEC_MAX_RECURSION) { + DMWARN_LIMIT("%s: FEC: recursion too deep", v->data_dev->name); + return -EIO; + } + + fio->level++; + if (type == DM_VERITY_BLOCK_TYPE_METADATA) block += v->data_blocks; @@ -470,7 +477,7 @@ int verity_fec_decode(struct dm_verity * if (r < 0) { r = fec_decode_rsb(v, io, fio, rsb, offset, true); if (r < 0) - return r; + goto done; } if (dest) @@ -480,6 +487,8 @@ int verity_fec_decode(struct dm_verity * r = verity_for_bv_block(v, io, iter, fec_bv_copy); } +done: + fio->level--; return r; } @@ -520,6 +529,7 @@ void verity_fec_init_io(struct dm_verity memset(fio->bufs, 0, sizeof(fio->bufs)); fio->nbufs = 0; fio->output = NULL; + fio->level = 0; } /* --- a/drivers/md/dm-verity-fec.h +++ b/drivers/md/dm-verity-fec.h @@ -27,6 +27,9 @@ #define DM_VERITY_FEC_BUF_MAX \ (1 << (PAGE_SHIFT - DM_VERITY_FEC_BUF_RS_BITS)) +/* maximum recursion level for verity_fec_decode */ +#define DM_VERITY_FEC_MAX_RECURSION 4 + #define DM_VERITY_OPT_FEC_DEV "use_fec_from_device" #define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks" #define DM_VERITY_OPT_FEC_START "fec_start" @@ -58,6 +61,7 @@ struct dm_verity_fec_io { unsigned nbufs; /* number of buffers allocated */ u8 *output; /* buffer for corrected output */ size_t output_pos; + unsigned level; /* recursion level */ }; #ifdef CONFIG_DM_VERITY_FEC