| Message ID | 148494392247.5256.10692618169002348643.stgit@birch.djwong.org (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On 1/20/17 2:25 PM, 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 <darrick.wong@oracle.com> > --- > 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. ok, but insane_agcount doesn't need to be global... > --- > 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; Not a fan of the global. Can you make it local, and then do something like this: if (sanitize_agount(&xmount, sbp)) insane_agount = true; > 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) Now this is always called with agno == 0, so is there any point to the arg? Eh, I guess it's fine. I can fix up the insane_agcount thing on the way in if you like. -Eric > +{ > + 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; > } > -- 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
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; }
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 <darrick.wong@oracle.com> --- 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(-) -- 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