From owner-svn-src-head@freebsd.org Sat Aug 29 09:22:33 2015 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 8F8BF9C4BB9; Sat, 29 Aug 2015 09:22:33 +0000 (UTC) (envelope-from delphij@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 744851F70; Sat, 29 Aug 2015 09:22:33 +0000 (UTC) (envelope-from delphij@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.70]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id t7T9MX8X007621; Sat, 29 Aug 2015 09:22:33 GMT (envelope-from delphij@FreeBSD.org) Received: (from delphij@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id t7T9MXhF007620; Sat, 29 Aug 2015 09:22:33 GMT (envelope-from delphij@FreeBSD.org) Message-Id: <201508290922.t7T9MXhF007620@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: delphij set sender to delphij@FreeBSD.org using -f From: Xin LI Date: Sat, 29 Aug 2015 09:22:33 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r287283 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 29 Aug 2015 09:22:33 -0000 Author: delphij Date: Sat Aug 29 09:22:32 2015 New Revision: 287283 URL: https://svnweb.freebsd.org/changeset/base/287283 Log: Fix a buffer overrun which may lead to data corruption, introduced in r286951 by reinstating changes in r274628. In l2arc_compress_buf(), we allocate a buffer to stash away the compressed data in 'cdata', allocated of l2hdr->b_asize bytes. We then ask zio_compress_data() to compress the buffer, b_l1hdr.b_tmp_cdata, which is of l2hdr->b_asize bytes, and have the compressed size (or original size, if compress didn't gain enough) stored in csize. To pad the buffer to fit the optimal write size, we round up the compressed size to L2 device's vdev_ashift. Illumos code rounds up the size by at most SPA_MINBLOCKSIZE. Because we know csize <= b_asize, and b_asize is integer multiple of SPA_MINBLOCKSIZE, we are guaranteed that the rounded up csize would be <= b_asize. However, this is not necessarily true when we round up to 1 << vdev_ashift, because it could be larger than SPA_MINBLOCKSIZE. So, in the worst case scenario, we are overwriting at most (1 << vdev_ashift - SPA_MINBLOCKSIZE) bytes of memory next to the compressed data buffer. Andriy's original change in r274628 reorganized the code a little bit, by moving the padding to after we determined that the compression was beneficial. At which point, we would check rounded size against the allocated buffer size, and the buffer overrun would not be possible. Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c ============================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Sat Aug 29 09:14:32 2015 (r287282) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Sat Aug 29 09:22:32 2015 (r287283) @@ -6529,13 +6529,6 @@ l2arc_compress_buf(arc_buf_hdr_t *hdr) csize = zio_compress_data(ZIO_COMPRESS_LZ4, hdr->b_l1hdr.b_tmp_cdata, cdata, l2hdr->b_asize); - rounded = P2ROUNDUP(csize, - (size_t)1 << l2hdr->b_dev->l2ad_vdev->vdev_ashift); - if (rounded > csize) { - bzero((char *)cdata + csize, rounded - csize); - csize = rounded; - } - if (csize == 0) { /* zero block, indicate that there's nothing to write */ zio_data_buf_free(cdata, len); @@ -6544,11 +6537,19 @@ l2arc_compress_buf(arc_buf_hdr_t *hdr) hdr->b_l1hdr.b_tmp_cdata = NULL; ARCSTAT_BUMP(arcstat_l2_compress_zeros); return (B_TRUE); - } else if (csize > 0 && csize < len) { + } + + rounded = P2ROUNDUP(csize, + (size_t)1 << l2hdr->b_dev->l2ad_vdev->vdev_ashift); + if (rounded < len) { /* * Compression succeeded, we'll keep the cdata around for * writing and release it afterwards. */ + if (rounded > csize) { + bzero((char *)cdata + csize, rounded - csize); + csize = rounded; + } HDR_SET_COMPRESS(hdr, ZIO_COMPRESS_LZ4); l2hdr->b_asize = csize; hdr->b_l1hdr.b_tmp_cdata = cdata;