commit 598bb8913d015150b7734b55443c0e53e7189fc7 upstream.
As reported by erofs-utils fuzzer, Lookback distance should be a positive number, so it should be actually looked back rather than spinning.
Fixes: 02827e1796b3 ("staging: erofs: add erofs_map_blocks_iter") Cc: stable@vger.kernel.org # 4.19+ Signed-off-by: Gao Xiang gaoxiang25@huawei.com Reviewed-by: Chao Yu yuchao0@huawei.com Link: https://lore.kernel.org/r/20190819103426.87579-7-gaoxiang25@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [ Gao Xiang: Since earlier kernels don't define EFSCORRUPTED, let's use EIO instead. ] Signed-off-by: Gao Xiang gaoxiang25@huawei.com --- drivers/staging/erofs/zmap.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/staging/erofs/zmap.c b/drivers/staging/erofs/zmap.c index c2359321ca13..30e6d02d30de 100644 --- a/drivers/staging/erofs/zmap.c +++ b/drivers/staging/erofs/zmap.c @@ -350,6 +350,12 @@ static int vle_extent_lookback(struct z_erofs_maprecorder *m,
switch (m->type) { case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD: + if (!m->delta[0]) { + errln("invalid lookback distance 0 at nid %llu", + vi->nid); + DBG_BUGON(1); + return -EIO; + } return vle_extent_lookback(m, m->delta[0]); case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN: map->m_flags &= ~EROFS_MAP_ZIPPED;