fs/iso9660: Fix invalid free

The ctx->filename can point to either a string literal or a dynamically
allocated string. The ctx->filename_alloc field is used to indicate the
type of allocation.

An issue has been identified where ctx->filename is reassigned to
a string literal in susp_iterate_dir() but ctx->filename_alloc is not
correctly handled. This oversight causes a memory leak and an invalid
free operation later.

The fix involves checking ctx->filename_alloc, freeing the allocated
string if necessary and clearing ctx->filename_alloc for string literals.

Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/grub-core/fs/iso9660.c b/grub-core/fs/iso9660.c
index 8d480e6022f4a79604ac8309d57a460e5a9b95a4..8e3c95c4f9b186ea1c52e9581065924519dad6a3 100644 (file)
--- a/grub-core/fs/iso9660.c
+++ b/grub-core/fs/iso9660.c
@@ -628,9 +628,19 @@ susp_iterate_dir (struct grub_iso9660_susp_entry *entry,
         filename type is stored.  */
       /* FIXME: Fix this slightly improper cast.  */
       if (entry->data[0] & GRUB_ISO9660_RR_DOT)
-       ctx->filename = (char *) ".";
+       {
+         if (ctx->filename_alloc)
+           grub_free (ctx->filename);
+         ctx->filename_alloc = 0;
+         ctx->filename = (char *) ".";
+       }
       else if (entry->data[0] & GRUB_ISO9660_RR_DOTDOT)
-       ctx->filename = (char *) "..";
+       {
+         if (ctx->filename_alloc)
+           grub_free (ctx->filename);
+         ctx->filename_alloc = 0;
+         ctx->filename = (char *) "..";
+       }
       else if (entry->len >= 5)
        {
          grub_size_t off = 0, csize = 1;