grub: add a fix for a memory leak

This patch adds a fix for a memory leak in grub's path construction
in zfs. It is a part of a security series [1].

[1] https://lists.gnu.org/archive/html/grub-devel/2021-03/msg00007.html

(From OE-Core rev: f2a474545b8ba61a43fcbcd3c375c5db9f0303ca)

Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 122 insertions, 0 deletions

diff --git a/meta/recipes-bsp/grub/files/0022-zfs-Fix-resource-leaks-while-constructing-path.patch b/meta/recipes-bsp/grub/files/0022-zfs-Fix-resource-leaks-while-constructing-path.patch
new file mode 100644
index 0000000000..5ded5520e9
--- /dev/null
+++ b/meta/recipes-bsp/grub/files/0022-zfs-Fix-resource-leaks-while-constructing-path.patch
@@ -0,0 +1,121 @@
+From 83fdffc07ec4586b375ab36189f255ffbd8f99c2 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>
+
+Upstream-Status: Backport [https://git.savannah.gnu.org/cgit/grub.git/commit/?id=89bdab965805e8d54d7f75349024e1a11cbe2eb8]
+Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.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 0c42cba..9087a72 100644
+--- a/grub-core/fs/zfs/zfs.c
++++ b/grub-core/fs/zfs/zfs.c
+@@ -2836,8 +2836,8 @@ 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);
+@@ -2879,11 +2879,18 @@ 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;
+@@ -2893,7 +2900,7 @@ 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;
+@@ -2903,6 +2910,8 @@ 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);
+@@ -2911,7 +2920,8 @@ 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)
+@@ -2949,11 +2959,12 @@ 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));
+@@ -2974,7 +2985,8 @@ 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;
diff --git a/meta/recipes-bsp/grub/grub2.inc b/meta/recipes-bsp/grub/grub2.inc
index 360e86685b..1630235edd 100644
--- a/meta/recipes-bsp/grub/grub2.inc
+++ b/meta/recipes-bsp/grub/grub2.inc
@@ -68,6 +68,7 @@ SRC_URI = "${GNU_MIRROR}/grub/grub-${PV}.tar.gz \
            file://0019-disk-cryptodisk-Fix-potential-integer-overflow.patch \
            file://0020-hfsplus-Check-that-the-volume-name-length-is-valid.patch \
            file://0021-zfs-Fix-possible-negative-shift-operation.patch \
+           file://0022-zfs-Fix-resource-leaks-while-constructing-path.patch \
            "
 SRC_URI[md5sum] = "5ce674ca6b2612d8939b9e6abed32934"
 SRC_URI[sha256sum] = "f10c85ae3e204dbaec39ae22fa3c5e99f0665417e91c2cb49b7e5031658ba6ea"