From: Dave Chinner dchinner@redhat.com
mainline inclusion from mainline-v6.4-rc6 commit edd8276dd70279c29d412d99b99c2c0cac1b2cdd category: bugfix bugzilla: 188883, https://gitee.com/openeuler/kernel/issues/I76JSK CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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The AGF verifier does not check that the AGF length field is within known good bounds. This has never been checked by runtime kernel code (i.e. the lack of verification goes back to 1993) yet we assume in many places that it is correct and verify other metdata against it.
Add length verification to the AGF verifier. The length of the AGF must be equal to the size of the AG specified in the superblock, unless it is the last AG in the filesystem. In that case, it must be less than or equal to sb->sb_agblocks and greater than XFS_MIN_AG_BLOCKS, which is the smallest AG a growfs operation will allow to exist.
This requires a bit of rework of the verifier function. We want to verify metadata before we use it to verify other metadata. Hence we need to verify the AGF sequence numbers before using them to verify the length of the AGF. Then we can verify the AGF length before we verify AGFL fields. Then we can verifier other fields that are bounds limited by the AGF length.
And, finally, by calculating agf_length only once into a local variable, we can collapse repeated "if (xfs_has_foo() &&" conditionaly checks into single checks. This makes the code much easier to follow as all the checks for a given feature are obviously in the same place.
Signed-off-by: Dave Chinner dchinner@redhat.com Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Darrick J. Wong djwong@kernel.org
Conflicts: fs/xfs/libxfs/xfs_alloc.c Signed-off-by: Long Li leo.lilong@huawei.com --- fs/xfs/libxfs/xfs_alloc.c | 89 ++++++++++++++++++++++++--------------- 1 file changed, 56 insertions(+), 33 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c index 0c99287d0d89..4a139583a905 100644 --- a/fs/xfs/libxfs/xfs_alloc.c +++ b/fs/xfs/libxfs/xfs_alloc.c @@ -2939,6 +2939,7 @@ xfs_agf_verify( { struct xfs_mount *mp = bp->b_mount; struct xfs_agf *agf = bp->b_addr; + uint32_t agf_length = be32_to_cpu(agf->agf_length);
if (xfs_has_crc(mp)) { if (!uuid_equal(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid)) @@ -2950,18 +2951,49 @@ xfs_agf_verify( if (!xfs_verify_magic(bp, agf->agf_magicnum)) return __this_address;
- if (!(XFS_AGF_GOOD_VERSION(be32_to_cpu(agf->agf_versionnum)) && - be32_to_cpu(agf->agf_freeblks) <= be32_to_cpu(agf->agf_length) && - be32_to_cpu(agf->agf_flfirst) < xfs_agfl_size(mp) && - be32_to_cpu(agf->agf_fllast) < xfs_agfl_size(mp) && - be32_to_cpu(agf->agf_flcount) <= xfs_agfl_size(mp))) + if (!XFS_AGF_GOOD_VERSION(be32_to_cpu(agf->agf_versionnum))) return __this_address;
- if (be32_to_cpu(agf->agf_length) > mp->m_sb.sb_dblocks) + /* + * Both agf_seqno and agf_length need to validated before anything else + * block number related in the AGF or AGFL can be checked. + * + * During growfs operations, the perag is not fully initialised, + * so we can't use it for any useful checking. growfs ensures we can't + * use it by using uncached buffers that don't have the perag attached + * so we can detect and avoid this problem. + */ + if (bp->b_pag && be32_to_cpu(agf->agf_seqno) != bp->b_pag->pag_agno) + return __this_address; + + /* + * Only the last AGF in the filesytsem is allowed to be shorter + * than the AG size recorded in the superblock. + */ + if (agf_length != mp->m_sb.sb_agblocks) { + /* + * During growfs, the new last AGF can get here before we + * have updated the superblock. Give it a pass on the seqno + * check. + */ + if (bp->b_pag && + be32_to_cpu(agf->agf_seqno) != mp->m_sb.sb_agcount - 1) + return __this_address; + if (agf_length < XFS_MIN_AG_BLOCKS) + return __this_address; + if (agf_length > mp->m_sb.sb_agblocks) + return __this_address; + } + + if (be32_to_cpu(agf->agf_flfirst) >= xfs_agfl_size(mp)) + return __this_address; + if (be32_to_cpu(agf->agf_fllast) >= xfs_agfl_size(mp)) + return __this_address; + if (be32_to_cpu(agf->agf_flcount) > xfs_agfl_size(mp)) return __this_address;
if (be32_to_cpu(agf->agf_freeblks) < be32_to_cpu(agf->agf_longest) || - be32_to_cpu(agf->agf_freeblks) > be32_to_cpu(agf->agf_length)) + be32_to_cpu(agf->agf_freeblks) > agf_length) return __this_address;
if (be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]) < 1 || @@ -2970,37 +3002,28 @@ xfs_agf_verify( be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNT]) > XFS_BTREE_MAXLEVELS) return __this_address;
- if (xfs_has_rmapbt(mp) && - (be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]) < 1 || - be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]) > XFS_BTREE_MAXLEVELS)) - return __this_address; - - if (xfs_has_rmapbt(mp) && - be32_to_cpu(agf->agf_rmap_blocks) > be32_to_cpu(agf->agf_length)) + if (xfs_has_lazysbcount(mp) && + be32_to_cpu(agf->agf_btreeblks) > agf_length) return __this_address;
- /* - * during growfs operations, the perag is not fully initialised, - * so we can't use it for any useful checking. growfs ensures we can't - * use it by using uncached buffers that don't have the perag attached - * so we can detect and avoid this problem. - */ - if (bp->b_pag && be32_to_cpu(agf->agf_seqno) != bp->b_pag->pag_agno) - return __this_address; + if (xfs_has_rmapbt(mp)) { + if (be32_to_cpu(agf->agf_rmap_blocks) > agf_length) + return __this_address;
- if (xfs_has_lazysbcount(mp) && - be32_to_cpu(agf->agf_btreeblks) > be32_to_cpu(agf->agf_length)) - return __this_address; + if (be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]) < 1 || + be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]) > + mp->m_rmap_maxlevels) + return __this_address; + }
- if (xfs_has_reflink(mp) && - be32_to_cpu(agf->agf_refcount_blocks) > - be32_to_cpu(agf->agf_length)) - return __this_address; + if (xfs_has_reflink(mp)) { + if (be32_to_cpu(agf->agf_refcount_blocks) > agf_length) + return __this_address;
- if (xfs_has_reflink(mp) && - (be32_to_cpu(agf->agf_refcount_level) < 1 || - be32_to_cpu(agf->agf_refcount_level) > XFS_BTREE_MAXLEVELS)) - return __this_address; + if (be32_to_cpu(agf->agf_refcount_level) < 1 || + be32_to_cpu(agf->agf_refcount_level) > mp->m_refc_maxlevels) + return __this_address; + }
return NULL;