From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Paulo Flabiano Smorigo <pfsmorigo@canonical.com>
Date: Mon, 14 Dec 2020 18:54:49 -0300
Subject: [PATCH] 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>
---
 grub-core/fs/zfs/zfs.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/grub-core/fs/zfs/zfs.c b/grub-core/fs/zfs/zfs.c
index f607b9b56b9..467fa7ee9ea 100644
--- a/grub-core/fs/zfs/zfs.c
+++ b/grub-core/fs/zfs/zfs.c
@@ -2771,8 +2771,8 @@ 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);
@@ -2815,7 +2815,11 @@ dnode_get_path (struct subvolume *subvol, const char *path_in, dnode_end_t *dn,
 
 	      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;
@@ -2823,7 +2827,10 @@ dnode_get_path (struct subvolume *subvol, const char *path_in, dnode_end_t *dn,
 
 		  err = dmu_read (&(dnode_path->dn), block, &t, 0, data);
 		  if (err)
-		    return err;
+		    {
+		      grub_free (sym_value);
+		      break;
+		    }
 
 		  movesize = sym_sz - block * blksz;
 		  if (movesize > blksz)
@@ -2832,13 +2839,18 @@ 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);
 	  if (!path_buf)
 	    {
 	      grub_free (oldpathbuf);
-	      return grub_errno;
+	      if (free_symval)
+		grub_free (sym_value);
+	      err = grub_errno;
+	      break;
 	    }
 	  grub_memcpy (path, sym_value, sym_sz);
 	  if (free_symval)
@@ -2876,11 +2888,12 @@ 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));
@@ -2901,7 +2914,8 @@ 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;