commit 0bc8061ffc733a0a246b8689b2d32a3e9204f43c upstream. syzbot reported a WARNING in iomap_iter_done: iomap_fiemap+0x73b/0x9b0 fs/iomap/fiemap.c:80 ioctl_fiemap fs/ioctl.c:220 [inline]
Generally, NONHEAD lclusters won't have delta[1]==0, except for crafted images and filesystems created by pre-1.0 mkfs versions. Previously, it would immediately bail out if delta[1]==0, which led to inadequate decompressed lengths (thus FIEMAP is impacted). Treat it as delta[1]=1 to work around these legacy mkfs versions. `lclusterbits > 14` is illegal for compact indexes, error out too. Reported-by: syzbot+6c0b301317aa0156f...@syzkaller.appspotmail.com Closes: https://lore.kernel.org/r/67373c0c.050a0220.2a2fcc.0079....@google.com Tested-by: syzbot+6c0b301317aa0156f...@syzkaller.appspotmail.com Fixes: d95ae5e25326 ("erofs: add support for the full decompressed length") Fixes: 001b8ccd0650 ("erofs: fix compact 4B support for 16k block size") CVE: CVE-2024-53234 Link: https://lore.kernel.org/r/20241115173651.3339514-1-hsiang...@linux.alibaba.com Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com> --- fs/erofs/zmap.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index 046eaaf16dad..2cd70cf4c8b2 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -256,7 +256,7 @@ static int compacted_load_cluster_from_disk(struct z_erofs_maprecorder *m, unsigned int amortizedshift; erofs_off_t pos; - if (lcn >= totalidx) + if (lcn >= totalidx || vi->z_logical_clusterbits > 14) return -EINVAL; m->lcn = lcn; @@ -441,7 +441,7 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m) u64 lcn = m->lcn, headlcn = map->m_la >> lclusterbits; int err; - do { + while (1) { /* handle the last EOF pcluster (no next HEAD lcluster) */ if ((lcn << lclusterbits) >= inode->i_size) { map->m_llen = inode->i_size - map->m_la; @@ -453,14 +453,16 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m) return err; if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) { - DBG_BUGON(!m->delta[1] && - m->clusterofs != 1 << lclusterbits); + /* work around invalid d1 generated by pre-1.0 mkfs */ + if (unlikely(!m->delta[1])) { + m->delta[1] = 1; + DBG_BUGON(1); + } } else if (m->type == Z_EROFS_LCLUSTER_TYPE_PLAIN || m->type == Z_EROFS_LCLUSTER_TYPE_HEAD1 || m->type == Z_EROFS_LCLUSTER_TYPE_HEAD2) { - /* go on until the next HEAD lcluster */ if (lcn != headlcn) - break; + break; /* ends at the next HEAD lcluster */ m->delta[1] = 1; } else { erofs_err(inode->i_sb, "unknown type %u @ lcn %llu of nid %llu", @@ -469,8 +471,7 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m) return -EOPNOTSUPP; } lcn += m->delta[1]; - } while (m->delta[1]); - + } map->m_llen = (lcn << lclusterbits) + m->clusterofs - map->m_la; return 0; } -- 2.43.5
