[SECURITY PATCH 037/117] zfs: Fix resource leaks while constructing path

[Daniel Kiper]

From: Paulo Flabiano Smorigo <pfsmorigo@canonical.com>

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>
---
 grub-core/fs/zfs/zfs.c | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/grub-core/fs/zfs/zfs.c b/grub-core/fs/zfs/zfs.c
index 695e6ea30..ca82eb878 100644
--- 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;
-- 
2.11.0