From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754622AbbLKOy1 (ORCPT ); Fri, 11 Dec 2015 09:54:27 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:19766 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752142AbbLKOyZ (ORCPT ); Fri, 11 Dec 2015 09:54:25 -0500 From: Vegard Nossum To: Jan Kara Cc: linux-kernel@vger.kernel.org, Vegard Nossum , stable@vger.kernel.org, Quentin Casasnovas , Andrew Morton Subject: [PATCH] udf: limit the maximum number of allocation extents Date: Fri, 11 Dec 2015 15:54:16 +0100 Message-Id: <1449845656-8974-1-git-send-email-vegard.nossum@oracle.com> X-Mailer: git-send-email 1.9.1 X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hit this kernel hang too while fuzzing. Please see this as a tentative patch indicating where the problem is -- I don't really know much about UDF or what an allocation extent is or whether there are more problems in the same neighbourhood. It looks like udf_truncate_extents() might also have a similar problem? Signed-off-by: Vegard Nossum Cc: stable@vger.kernel.org Cc: Jan Kara Cc: Quentin Casasnovas Cc: Andrew Morton --- fs/udf/inode.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git fs/udf/inode.c fs/udf/inode.c index 8d0b3ad..e1875f5 100644 --- fs/udf/inode.c +++ fs/udf/inode.c @@ -2047,13 +2047,26 @@ void udf_write_aext(struct inode *inode, struct extent_position *epos, epos->offset += adsize; } +/* + * Maximum number of allocation extents. The chosen number is + * arbitrary - just that we hopefully don't limit any real use + * but avoid looping for too long on corrupted media. + */ +#define UDF_MAX_AEXT_NESTING 4096 + int8_t udf_next_aext(struct inode *inode, struct extent_position *epos, struct kernel_lb_addr *eloc, uint32_t *elen, int inc) { int8_t etype; + unsigned int indirections = 0; while ((etype = udf_current_aext(inode, epos, eloc, elen, inc)) == (EXT_NEXT_EXTENT_ALLOCDECS >> 30)) { + if (++indirections > UDF_MAX_AEXT_NESTING) { + udf_err(inode->i_sb, "too many AEXTs (max %u supported)\n", UDF_MAX_AEXT_NESTING); + return -1; + } + int block; epos->block = *eloc; epos->offset = sizeof(struct allocExtDesc); -- 1.9.1