f2fs: Fix gcc9 error -Werror=maybe-uninitialized

The function grub_get_node_path() could return uninitialized offset with
level == 0 if the block is greater than direct_index + 2 * direct_blks +
2 * indirect_blks + dindirect_blks. The uninitialized offset is then used
by function grub_f2fs_get_block() because level == 0 is valid and
meaningful return to be processed.

The fix is to set level = -1 as return value by grub_get_node_path() to
signify an error that the input block cannot be handled. Any caller
should therefore check level is negative or not before processing the
output.

Reported-by: Neil MacLeod <neil@nmacleod.com>
Signed-off-by: Michael Chang <mchang@suse.com>
Tested-by: Neil MacLeod <neil@nmacleod.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/grub-core/fs/f2fs.c b/grub-core/fs/f2fs.c
index 644653dbe2afa0781a75f23283752082ad370838..bb28b291bd9bcc677b136abecb6a8941add391bc 100644 (file)
--- a/grub-core/fs/f2fs.c
+++ b/grub-core/fs/f2fs.c
@@ -702,7 +702,7 @@ grub_get_node_path (struct grub_f2fs_inode *inode, grub_uint32_t block,
   grub_uint32_t dindirect_blks = indirect_blks * NIDS_PER_BLOCK;
   grub_uint32_t direct_index = DEF_ADDRS_PER_INODE;
   int n = 0;
-  int level = 0;
+  int level = -1;
 
   if (inode->i_inline & F2FS_INLINE_XATTR)
     direct_index -= F2FS_INLINE_XATTR_ADDRS;
@@ -712,6 +712,7 @@ grub_get_node_path (struct grub_f2fs_inode *inode, grub_uint32_t block,
   if (block < direct_index)
     {
       offset[n] = block;
+      level = 0;
       goto got;
     }
 
@@ -860,6 +861,10 @@ grub_f2fs_get_block (grub_fshelp_node_t node, grub_disk_addr_t block_ofs)
   int level, i;
 
   level = grub_get_node_path (inode, block_ofs, offset, noffset);
+
+  if (level < 0)
+    return -1;
+
   if (level == 0)
     return grub_le_to_cpu32 (inode->i_addr[offset[0]]);