From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:24230 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753183AbdATUZe (ORCPT ); Fri, 20 Jan 2017 15:25:34 -0500 Subject: [PATCH 1/5] xfs_db: sanitize geometry on load From: "Darrick J. Wong" Date: Fri, 20 Jan 2017 12:25:22 -0800 Message-ID: <148494392247.5256.10692618169002348643.stgit@birch.djwong.org> In-Reply-To: <148494391629.5256.3328772079712970611.stgit@birch.djwong.org> References: <148494391629.5256.3328772079712970611.stgit@birch.djwong.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: sandeen@redhat.com, darrick.wong@oracle.com Cc: linux-xfs@vger.kernel.org xfs_db doesn't check the filesystem geometry when it's mounting, which means that garbage agcount values can cause OOMs when we try to allocate all the per-AG incore metadata. If we see geometry that looks suspicious, try to derive the actual AG geometry to avoid crashing the system. This should help with xfs/1301 fuzzing. Signed-off-by: Darrick J. Wong --- v2: Only modify sb_ag{blocks,count} if they seem insane -- use local variables to avoid screwing up the rest of the metadata. v3: Suggest a possible agcount value, but always restrict to 1 AG. v4: Remove the suggested agcount value and make sure we can't exit the program with an exitcode of zero. --- db/init.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 74 insertions(+), 10 deletions(-) diff --git a/db/init.c b/db/init.c index ec1e274..e60ac66 100644 --- a/db/init.c +++ b/db/init.c @@ -41,6 +41,7 @@ struct xfs_mount *mp; struct xlog xlog; libxfs_init_t x; xfs_agnumber_t cur_agno = NULLAGNUMBER; +static bool insane_agcount; static void usage(void) @@ -51,13 +52,80 @@ usage(void) exit(1); } +/* Try to load a superblock for the given agno, no verifiers. */ +static bool +load_sb( + struct xfs_mount *mp, + xfs_agnumber_t agno, + struct xfs_sb *sbp) +{ + struct xfs_buf *bp; + + bp = libxfs_readbuf(mp->m_ddev_targp, + XFS_AG_DADDR(mp, agno, XFS_SB_DADDR), + 1 << (XFS_MAX_SECTORSIZE_LOG - BBSHIFT), 0, NULL); + + if (!bp || bp->b_error) + return false; + + /* copy SB from buffer to in-core, converting architecture as we go */ + libxfs_sb_from_disk(sbp, XFS_BUF_TO_SBP(bp)); + libxfs_putbuf(bp); + libxfs_purgebuf(bp); + + return true; +} + +/* + * If the agcount doesn't look sane, suggest a real agcount to the user, + * and pretend agcount = 1 to avoid OOMing libxfs_initialize_perag. + */ +static void +sanitize_geometry( + struct xfs_mount *mp, + struct xfs_sb *sbp) +{ + unsigned int blocklog; + unsigned int blocksize; + unsigned long long dblocks; + + /* If the geometry looks ok, we're done. */ + if (sbp->sb_blocklog >= XFS_MIN_BLOCKSIZE_LOG && + sbp->sb_blocklog <= XFS_MAX_BLOCKSIZE_LOG && + sbp->sb_blocksize == (1 << sbp->sb_blocklog) && + sbp->sb_dblocks * sbp->sb_blocksize <= x.dsize * x.dbsize && + sbp->sb_dblocks <= XFS_MAX_DBLOCKS(sbp) && + sbp->sb_dblocks >= XFS_MIN_DBLOCKS(sbp)) + return; + + /* Check blocklog and blocksize */ + blocklog = sbp->sb_blocklog; + blocksize = sbp->sb_blocksize; + if (blocklog < XFS_MIN_BLOCKSIZE_LOG || + blocklog > XFS_MAX_BLOCKSIZE_LOG) + blocklog = libxfs_log2_roundup(blocksize); + if (blocksize != (1 << blocklog)) + blocksize = (1 << blocksize); + + /* Clamp dblocks to the size of the device. */ + dblocks = sbp->sb_dblocks; + if (dblocks > x.dsize * x.dbsize / blocksize) + dblocks = x.dsize * x.dbsize / blocksize; + + /* Assume 1 AG to avoid OOM. */ + fprintf(stderr, +_("%s: device %s AG count is insane. Limiting reads to AG 0.\n"), + progname, fsdevice); + sbp->sb_agcount = 1; + insane_agcount = true; +} + void init( int argc, char **argv) { struct xfs_sb *sbp; - struct xfs_buf *bp; int c; setlocale(LC_ALL, ""); @@ -124,20 +192,12 @@ init( */ memset(&xmount, 0, sizeof(struct xfs_mount)); libxfs_buftarg_init(&xmount, x.ddev, x.logdev, x.rtdev); - bp = libxfs_readbuf(xmount.m_ddev_targp, XFS_SB_DADDR, - 1 << (XFS_MAX_SECTORSIZE_LOG - BBSHIFT), 0, NULL); - - if (!bp || bp->b_error) { + if (!load_sb(&xmount, 0, &xmount.m_sb)) { fprintf(stderr, _("%s: %s is invalid (cannot read first 512 " "bytes)\n"), progname, fsdevice); exit(1); } - /* copy SB from buffer to in-core, converting architecture as we go */ - libxfs_sb_from_disk(&xmount.m_sb, XFS_BUF_TO_SBP(bp)); - libxfs_putbuf(bp); - libxfs_purgebuf(bp); - sbp = &xmount.m_sb; if (sbp->sb_magicnum != XFS_SB_MAGIC) { fprintf(stderr, _("%s: %s is not a valid XFS filesystem (unexpected SB magic number 0x%08x)\n"), @@ -148,6 +208,8 @@ init( } } + sanitize_geometry(&xmount, sbp); + mp = libxfs_mount(&xmount, sbp, x.ddev, x.logdev, x.rtdev, LIBXFS_MOUNT_DEBUGGER); if (!mp) { @@ -230,5 +292,7 @@ main( libxfs_device_close(x.logdev); if (x.rtdev) libxfs_device_close(x.rtdev); + if (insane_agcount && exitcode == 0) + exitcode = 1; return exitcode; }