staging: erofs: fix conditional uninitialized `pcn' in z_erofs_map_blocks_iter

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
index 0e410a2..bd2d7a8 100644 (file)
--- 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 @@ out:
        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;
 }