[PATCH 2/2] staging: erofs: fix conditional uninitialized `pcn' in z_erofs_map_blocks_iter

Gao Xiang
2018-07-29T05:38:12Z

This patch adds error handling code for
z_erofs_map_blocks_iter to fix the compiler blame.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---

let's solve the compiler warning first, more error handling code
for other functions will be added in the future patch.

drivers/staging/erofs/unzip_vle.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
index 0e410a228cd4..bd2d7a8d5085 100644
--- a/drivers/staging/erofs/unzip_vle.c
+++ b/drivers/staging/erofs/unzip_vle.c
@@ -1532,13 +1532,14 @@ int z_erofs_map_blocks_iter(struct inode *inode,
unsigned long long ofs, end;
struct z_erofs_vle_decompressed_index *di;
erofs_blk_t e_blkaddr, pcn;
- unsigned lcn, logical_cluster_ofs;
+ unsigned lcn, logical_cluster_ofs, cluster_type;
u32 ofs_rem;
struct page *mpage = *mpage_ret;
void *kaddr;
bool initial;
const unsigned int clusterbits = EROFS_SB(inode->i_sb)->clusterbits;
const unsigned int clustersize = 1 << clusterbits;
+ int err = 0;

/* if both m_(l,p)len are 0, regularize l_lblk, l_lofs, etc... */
initial = !map->m_llen;
@@ -1592,7 +1593,9 @@ int z_erofs_map_blocks_iter(struct inode *inode,

end = (u64)(lcn + 1) * clustersize;

- switch (vle_cluster_type(di)) {
+ cluster_type = vle_cluster_type(di);
+
+ switch (cluster_type) {
case Z_EROFS_VLE_CLUSTER_TYPE_PLAIN:
if (ofs_rem >= logical_cluster_ofs)
map->m_flags ^= EROFS_MAP_ZIPPED;
@@ -1608,13 +1611,24 @@ int z_erofs_map_blocks_iter(struct inode *inode,
break;
}

- BUG_ON(!lcn); /* logical cluster number >= 1 */
+ /* logical cluster number should be >= 1 */
+ if (unlikely(!lcn)) {
+ errln("invalid logical cluster 0 at nid %llu",
+ EROFS_V(inode)->nid);
+ err = -EIO;
+ goto unmap_out;
+ }
end = (lcn-- * clustersize) | logical_cluster_ofs;
case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:
/* get the correspoinding first chunk */
ofs = vle_get_logical_extent_head(inode, mpage_ret,
&kaddr, lcn, &pcn, &map->m_flags);
mpage = *mpage_ret;
+ default:
+ errln("unknown cluster type %u at offset %llu of nid %llu",
+ cluster_type, ofs, EROFS_V(inode)->nid);
+ err = -EIO;
+ goto unmap_out;
}

map->m_la = ofs;
@@ -1630,6 +1644,9 @@ int z_erofs_map_blocks_iter(struct inode *inode,
debugln("%s, m_la %llu m_pa %llu m_llen %llu m_plen %llu m_flags 0%o",
__func__, map->m_la, map->m_pa,
map->m_llen, map->m_plen, map->m_flags);
- return 0;
+
+ /* aggressively BUG_ON iff CONFIG_EROFS_FS_DEBUG is on */
+ DBG_BUGON(err < 0);
+ return err;
}

--
2.17.1