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Wong" , Christoph Hellwig , Carlos Maiolino , Sasha Levin Subject: [PATCH 7.3.y 2/2] xfs: improve dirent bounds checking in scrub and repair Date: Thu, 5 Nov 2026 10:47:17 -0500 Message-ID: <20261105154711.2078714-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261105154711.2078714-1-sashal@kernel.org> References: <2026110438-devouring-spool-0e9a@gregkh> <20261105154711.2078714-1-sashal@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Darrick J. Wong" [ Upstream commit 5d470234d04dae6fe2ca2cf4b9ef277b78c7e05a ] LOLLM complains that we don't do enough bounds checking of the directory entries in directory blocks when we're looking for errors or trying to salvage entries. Let's improve that with more detailed checks. Cc: stable@vger.kernel.org # v4.16 Fixes: ce92d29ddf9908 ("xfs: directory scrubber must walk through data block to offset") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino Signed-off-by: Sasha Levin --- fs/xfs/scrub/dir.c | 68 +++++++++++++++++++++++++++++++++------ fs/xfs/scrub/dir_repair.c | 37 ++++++++++++++++++--- 2 files changed, 91 insertions(+), 14 deletions(-) diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c index e35631e00ddec..05fe8bc71427e 100644 --- a/fs/xfs/scrub/dir.c +++ b/fs/xfs/scrub/dir.c @@ -323,11 +323,24 @@ xchk_dir_check_unused( struct xchk_da_btree *ds, struct xfs_buf *bp, unsigned int iter_off, - unsigned int end) + unsigned int end, + xfs_dablk_t rec_bno) { struct xfs_dir2_data_unused *dup = bp->b_addr + iter_off; + unsigned int advance; + + if (iter_off + sizeof(*dup) > end) { + xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno); + return -1; + } + + advance = xfs_dir2_data_unusedsize(be16_to_cpu(dup->length)); + if (!advance || iter_off + advance > end) { + xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno); + return -1; + } - return be16_to_cpu(dup->length); + return advance; } /* @@ -341,15 +354,31 @@ xchk_dir_check_entry( struct xfs_buf *bp, unsigned int iter_off, unsigned int end, - struct xfs_dir2_data_entry *dent) + struct xfs_dir2_data_entry *dent, + xfs_dablk_t rec_bno) { struct xfs_dir2_data_entry *dep = bp->b_addr + iter_off; struct xfs_mount *mp = ds->state->mp; + unsigned int advance; + + /* must have namelen */ + advance = offsetof(typeof(*dep), name); + if (iter_off + advance >= end) { + xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno); + return -1; + } + + /* Don't walk off the end of the block. */ + advance = xfs_dir2_data_entsize(mp, dep->namelen); + if (!advance || iter_off + advance > end) { + xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno); + return -1; + } if (dep == dent) return 0; - return xfs_dir2_data_entsize(mp, dep->namelen); + return advance; } /* Scrub a directory btree record. */ @@ -377,6 +406,7 @@ xchk_dir_rec( xfs_dahash_t hash; struct xfs_dir3_icleaf_hdr hdr; unsigned int tag; + bool foundit = false; int error; ASSERT(blk->magic == XFS_DIR2_LEAF1_MAGIC || @@ -421,33 +451,44 @@ xchk_dir_rec( dent = bp->b_addr + off; /* Make sure we got a real directory entry. */ - iter_off = geo->data_entry_offset; end = xfs_dir3_data_end_offset(geo, bp->b_addr); if (!end) { xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno); goto out_relse; } - for (;;) { + iter_off = geo->data_entry_offset; + while (iter_off < end) { struct xfs_dir2_data_unused *dup = bp->b_addr + iter_off; int advance; - if (iter_off >= end) { + /* must have freetag */ + advance = offsetof(typeof(*dup), length); + if (iter_off + advance >= end) { xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno); goto out_relse; } if (dup->freetag == cpu_to_be16(XFS_DIR2_DATA_FREE_TAG)) - advance = xchk_dir_check_unused(ds, bp, iter_off, end); + advance = xchk_dir_check_unused(ds, bp, iter_off, end, + rec_bno); else advance = xchk_dir_check_entry(ds, bp, iter_off, end, - dent); + dent, rec_bno); if (advance < 0) goto out_relse; - if (!advance) + if (!advance) { + foundit = true; break; + } iter_off += advance; } + /* Hash tree must point to the exact dirent */ + if (!foundit) { + xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno); + goto out_relse; + } + /* Retrieve the entry, sanity check it, and compare hashes. */ ino = be64_to_cpu(dent->inumber); hash = be32_to_cpu(ent->hashval); @@ -459,6 +500,13 @@ xchk_dir_rec( goto out_relse; } + /* Name must not overflow end of block */ + if ((char *)dent->name + dent->namelen > + (char *)bp->b_addr + BBTOB(bp->b_length)) { + xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno); + goto out_relse; + } + /* Does the directory hash match? */ dname.name = dent->name; dname.len = dent->namelen; diff --git a/fs/xfs/scrub/dir_repair.c b/fs/xfs/scrub/dir_repair.c index 1169a2ad26876..84fe3dda0d421 100644 --- a/fs/xfs/scrub/dir_repair.c +++ b/fs/xfs/scrub/dir_repair.c @@ -473,8 +473,16 @@ xrep_dir_recover_unused( unsigned int end) { struct xfs_dir2_data_unused *dup = bp->b_addr + offset; + unsigned int advance; + + if (offset + sizeof(*dup) > end) + return 0; + + advance = xfs_dir2_data_unusedsize(be16_to_cpu(dup->length)); + if (!advance || offset + advance > end) + return 0; - return be16_to_cpu(dup->length); + return advance; } /* @@ -492,11 +500,14 @@ xrep_dir_recover_entry( unsigned int advance; int error; + /* must have namelen */ + advance = offsetof(typeof(*dep), name); + if (offset + advance >= end) + return 0; + /* Don't walk off the end of the block. */ advance = xfs_dir2_data_entsize(rd->sc->mp, dep->namelen); - if (!advance) - return 0; - if (offset + advance > end) + if (!advance || offset + advance > end) return 0; /* Ok, let's save this entry. */ @@ -534,6 +545,11 @@ xrep_dir_recover_data( if (xchk_should_terminate(rd->sc, &error)) return error; + /* must have freetag */ + advance = offsetof(typeof(*dup), length); + if (offset + advance >= end) + break; + if (dup->freetag == cpu_to_be16(XFS_DIR2_DATA_FREE_TAG)) advance = xrep_dir_recover_unused(bp, offset, end); else @@ -565,6 +581,19 @@ xrep_dir_recover_sf( hdr = ifp->if_data; end = (unsigned char *)ifp->if_data + ifp->if_bytes; + /* sf header must be big enough for count/i8count */ + if (!hdr || ifp->if_bytes < 2) + return 0; + + /* and large enough for the parent inumber */ + if (hdr->i8count) { + if (ifp->if_bytes < offsetof(struct xfs_dir2_sf_hdr, parent[8])) + return 0; + } else { + if (ifp->if_bytes < offsetof(struct xfs_dir2_sf_hdr, parent[4])) + return 0; + } + ino = xfs_dir2_sf_get_parent_ino(hdr); trace_xrep_dir_salvaged_parent(rd->sc->ip, ino); -- 2.53.0