[PATCH] Avoid NULL pointer dereference in progress module.

[dann frazier <dann.frazier@canonical.com>]

grub_net_fs_open() saves off a copy of the file structure it gets passed and
uses it to create a bufio structure. It then overwrites the passed in file
structure with this new bufio structure. Since file->name doesn't get set
until we return back to grub_file_open(), it means that only the bufio
structure gets a valid file->name. The "real" file's name is left
uninitialized. This leads to a crash when the progress module hook is called
on it. Fix this by adding a copy of the filename during the switcheroo.
grub_file_close() will free that string in the success case, we only need
to handle the free in an error. While we're at it, also fix a leaked file
structure in the case that grub_strdup() fails when setting
file->device->net->name.

Finally, make progress more robust by checking for NULL before reading the
name. Andrei noticed that this could occur if grub_strdup() fails in
grub_file_open().

Signed-off-by: dann frazier <dann.frazier@canonical.com>
---
 grub-core/lib/progress.c |  3 +--
 grub-core/net/net.c      | 14 +++++++++++++-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/grub-core/lib/progress.c b/grub-core/lib/progress.c
index 63a0767..2775554 100644
--- a/grub-core/lib/progress.c
+++ b/grub-core/lib/progress.c
@@ -70,8 +70,7 @@ grub_file_progress_hook_real (grub_disk_addr_t sector __attribute__ ((unused)),
 	percent = grub_divmod64 (100 * file->progress_offset,
 				 file->size, 0);
 
-      partial_file_name = grub_strrchr (file->name, '/');
-      if (partial_file_name)
+      if (file->name && (partial_file_name = grub_strrchr (file->name, '/')))
 	partial_file_name++;
       else
 	partial_file_name = "";
diff --git a/grub-core/net/net.c b/grub-core/net/net.c
index 21a4e94..9f83765 100644
--- a/grub-core/net/net.c
+++ b/grub-core/net/net.c
@@ -1391,7 +1391,17 @@ grub_net_fs_open (struct grub_file *file_out, const char *name)
   file->device->net->packs.last = NULL;
   file->device->net->name = grub_strdup (name);
   if (!file->device->net->name)
-    return grub_errno;
+    {
+      grub_free (file);
+      return grub_errno;
+    }
+  file->name = grub_strdup (name);
+  if (!file->name)
+    {
+      grub_free (file->device->net->name);
+      grub_free (file);
+      return grub_errno;
+    }
 
   err = file->device->net->protocol->open (file, name);
   if (err)
@@ -1401,6 +1411,7 @@ grub_net_fs_open (struct grub_file *file_out, const char *name)
 	  grub_netbuff_free (file->device->net->packs.first->nb);
 	  grub_net_remove_packet (file->device->net->packs.first);
 	}
+      grub_free (file->name);
       grub_free (file->device->net->name);
       grub_free (file);
       return err;
@@ -1414,6 +1425,7 @@ grub_net_fs_open (struct grub_file *file_out, const char *name)
 	  grub_net_remove_packet (file->device->net->packs.first);
 	}
       file->device->net->protocol->close (file);
+      grub_free (file->name);
       grub_free (file->device->net->name);
       grub_free (file);
       return grub_errno;
-- 
2.5.0