zfs: Fix resource leaks while constructing path

There are several exit points in dnode_get_path() that are causing possible
memory leaks.

In the while(1) the correct exit mechanism should not be to do a direct return,
but to instead break out of the loop, setting err first if it is not already set.

The reason behind this is that the dnode_path is a linked list, and while doing
through this loop, it is being allocated and built up - the only way to
correctly unravel it is to traverse it, which is what is being done at the end
of the function outside of the loop.

Several of the existing exit points correctly did a break, but not all so this
change makes that more consistent and should resolve the leaking of memory as
found by Coverity.

Fixes: CID 73741
Signed-off-by: Paulo Flabiano Smorigo <pfsmorigo@canonical.com>
Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/grub-core/fs/zfs/zfs.c b/grub-core/fs/zfs/zfs.c
index 695e6ea308142975f11dbe548d4cad79cf3e110f..ca82eb878207efac79d2be96f5ce41f53381c020 100644 (file)
--- a/grub-core/fs/zfs/zfs.c
+++ b/grub-core/fs/zfs/zfs.c
@@ -2839,8 +2839,8 @@ dnode_get_path (struct subvolume *subvol, const char *path_in, dnode_end_t *dn,
 
       if (dnode_path->dn.dn.dn_type != DMU_OT_DIRECTORY_CONTENTS)
        {
-         grub_free (path_buf);
-         return grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("not a directory"));
+         err = grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("not a directory"));
+         break;
        }
       err = zap_lookup (&(dnode_path->dn), cname, &objnum,
                        data, subvol->case_insensitive);
@@ -2882,11 +2882,18 @@ dnode_get_path (struct subvolume *subvol, const char *path_in, dnode_end_t *dn,
                       << SPA_MINBLOCKSHIFT);
 
              if (blksz == 0)
-               return grub_error(GRUB_ERR_BAD_FS, "0-sized block");
+                {
+                  err = grub_error (GRUB_ERR_BAD_FS, "0-sized block");
+                  break;
+                }
 
              sym_value = grub_malloc (sym_sz);
              if (!sym_value)
-               return grub_errno;
+               {
+                 err = grub_errno;
+                 break;
+               }
+
              for (block = 0; block < (sym_sz + blksz - 1) / blksz; block++)
                {
                  void *t;
@@ -2896,7 +2903,7 @@ dnode_get_path (struct subvolume *subvol, const char *path_in, dnode_end_t *dn,
                  if (err)
                    {
                      grub_free (sym_value);
-                     return err;
+                     break;
                    }
 
                  movesize = sym_sz - block * blksz;
@@ -2906,6 +2913,8 @@ dnode_get_path (struct subvolume *subvol, const char *path_in, dnode_end_t *dn,
                  grub_memcpy (sym_value + block * blksz, t, movesize);
                  grub_free (t);
                }
+               if (err)
+                 break;
              free_symval = 1;
            }       
          path = path_buf = grub_malloc (sym_sz + grub_strlen (oldpath) + 1);
@@ -2914,7 +2923,8 @@ dnode_get_path (struct subvolume *subvol, const char *path_in, dnode_end_t *dn,
              grub_free (oldpathbuf);
              if (free_symval)
                grub_free (sym_value);
-             return grub_errno;
+             err = grub_errno;
+             break;
            }
          grub_memcpy (path, sym_value, sym_sz);
          if (free_symval)
@@ -2952,11 +2962,12 @@ dnode_get_path (struct subvolume *subvol, const char *path_in, dnode_end_t *dn,
              
              err = zio_read (bp, dnode_path->dn.endian, &sahdrp, NULL, data);
              if (err)
-               return err;
+               break;
            }
          else
            {
-             return grub_error (GRUB_ERR_BAD_FS, "filesystem is corrupt");
+             err = grub_error (GRUB_ERR_BAD_FS, "filesystem is corrupt");
+             break;
            }
 
          hdrsize = SA_HDR_SIZE (((sa_hdr_phys_t *) sahdrp));
@@ -2977,7 +2988,8 @@ dnode_get_path (struct subvolume *subvol, const char *path_in, dnode_end_t *dn,
              if (!path_buf)
                {
                  grub_free (oldpathbuf);
-                 return grub_errno;
+                 err = grub_errno;
+                 break;
                }
              grub_memcpy (path, sym_value, sym_sz);
              path [sym_sz] = 0;