From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:50152 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750705AbdAWVan (ORCPT ); Mon, 23 Jan 2017 16:30:43 -0500 Date: Mon, 23 Jan 2017 13:30:38 -0800 From: "Darrick J. Wong" Subject: Re: [PATCH v5 1/5] xfs_db: sanitize geometry on load Message-ID: <20170123213038.GC31202@birch.djwong.org> References: <148494391629.5256.3328772079712970611.stgit@birch.djwong.org> <148494392247.5256.10692618169002348643.stgit@birch.djwong.org> <20170121001505.GK12985@birch.djwong.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170121001505.GK12985@birch.djwong.org> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: sandeen@redhat.com Cc: linux-xfs@vger.kernel.org On Fri, Jan 20, 2017 at 04:15:05PM -0800, Darrick J. Wong wrote: > 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. > v5: remove global variables and unnecessary parameters > --- > db/init.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 77 insertions(+), 12 deletions(-) > > diff --git a/db/init.c b/db/init.c > index ec1e274..0c684a5 100644 > --- a/db/init.c > +++ b/db/init.c > @@ -51,13 +51,81 @@ usage(void) > exit(1); > } > > +/* Try to load a superblock for the given agno, no verifiers. */ > +static bool > +load_sb( > + struct xfs_mount *mp, > + struct xfs_sb *sbp) > +{ > + struct xfs_buf *bp; > + > + bp = libxfs_readbuf(mp->m_ddev_targp, 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. > + * Returns true if the geometry was sane. > + */ > +static bool > +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 true; > + > + /* 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; NAK, this is dead code and the comments are wrong. Sending v6. --D > + > + /* 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; > + > + return false; > +} > + > void > init( > int argc, > - char **argv) > + char **argv, > + bool *insane_agcount) > { > 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, &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( > } > } > > + *insane_agcount = !sanitize_geometry(&xmount, sbp); > + > mp = libxfs_mount(&xmount, sbp, x.ddev, x.logdev, x.rtdev, > LIBXFS_MOUNT_DEBUGGER); > if (!mp) { > @@ -190,10 +252,11 @@ main( > int c, i, done = 0; > char *input; > char **v; > + bool insane_agcount; > int start_iocur_sp; > > pushfile(stdin); > - init(argc, argv); > + init(argc, argv, &insane_agcount); > start_iocur_sp = iocur_sp; > > for (i = 0; !done && i < ncmdline; i++) { > @@ -230,5 +293,7 @@ main( > libxfs_device_close(x.logdev); > if (x.rtdev) > libxfs_device_close(x.rtdev); > + if (insane_agcount && exitcode == 0) > + exitcode = 1; > return exitcode; > } > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html