From bfc4ccb1584129d3ef051f8bf6155835374f132f Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Wed, 21 Aug 2019 11:09:08 +0800 Subject: staging: erofs: avoid loop in submit chains As reported by erofs-utils fuzzer, 2 conditions can happen in corrupted images, which can cause unexpected behaviors. - access the same pcluster one more time; - access the tail end pcluster again, e.g. _ access again (will trigger tail merging) | 1 2 3 1 2 -> 1 2 3 1 |_ tail end of the chain \___/ (unexpected behavior) Let's detect and avoid them now. Reviewed-by: Chao Yu Signed-off-by: Gao Xiang Link: https://lore.kernel.org/r/20190821030908.40282-1-gaoxiang25@huawei.com Signed-off-by: Greg Kroah-Hartman --- drivers/staging/erofs/zdata.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/staging/erofs/zdata.c b/drivers/staging/erofs/zdata.c index 23283c97fd3b..4d6faaab04f5 100644 --- a/drivers/staging/erofs/zdata.c +++ b/drivers/staging/erofs/zdata.c @@ -132,7 +132,7 @@ enum z_erofs_collectmode { struct z_erofs_collector { struct z_erofs_pagevec_ctor vector; - struct z_erofs_pcluster *pcl; + struct z_erofs_pcluster *pcl, *tailpcl; struct z_erofs_collection *cl; struct page **compressedpages; z_erofs_next_pcluster_t owned_head; @@ -353,6 +353,11 @@ static struct z_erofs_collection *cllookup(struct z_erofs_collector *clt, return NULL; pcl = container_of(grp, struct z_erofs_pcluster, obj); + if (clt->owned_head == &pcl->next || pcl == clt->tailpcl) { + DBG_BUGON(1); + erofs_workgroup_put(grp); + return ERR_PTR(-EFSCORRUPTED); + } cl = z_erofs_primarycollection(pcl); if (unlikely(cl->pageofs != (map->m_la & ~PAGE_MASK))) { @@ -381,7 +386,13 @@ static struct z_erofs_collection *cllookup(struct z_erofs_collector *clt, } } mutex_lock(&cl->lock); + /* used to check tail merging loop due to corrupted images */ + if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL) + clt->tailpcl = pcl; clt->mode = try_to_claim_pcluster(pcl, &clt->owned_head); + /* clean tailpcl if the current owned_head is Z_EROFS_PCLUSTER_TAIL */ + if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL) + clt->tailpcl = NULL; clt->pcl = pcl; clt->cl = cl; return cl; @@ -434,6 +445,9 @@ static struct z_erofs_collection *clregister(struct z_erofs_collector *clt, kmem_cache_free(pcluster_cachep, pcl); return ERR_PTR(-EAGAIN); } + /* used to check tail merging loop due to corrupted images */ + if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL) + clt->tailpcl = pcl; clt->owned_head = &pcl->next; clt->pcl = pcl; clt->cl = cl; -- cgit v1.2.3