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staging: erofs: avoid endless loop of invalid lookback distance 0

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As reported by erofs-utils fuzzer, Lookback distance should
be a positive number, so it should be actually looked back
rather than spinning.

Fixes: 02827e1796 ("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>
This commit is contained in:
Gao Xiang 2019-08-19 18:34:26 +08:00 committed by Greg Kroah-Hartman
parent 138e1a0990
commit 598bb8913d
1 changed files with 6 additions and 0 deletions
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6
drivers/staging/erofs/zmap.c
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@ -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 (unlikely(!m->delta[0])) {
errln("invalid lookback distance 0 at nid %llu",
vi->nid);
DBG_BUGON(1);
return -EFSCORRUPTED;
}
return vle_extent_lookback(m, m->delta[0]);
case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
map->m_flags &= ~EROFS_MAP_ZIPPED;