[PATCH v2 4/5] fs/iso9660: Incorrect check for entry boundary

[Lidong Chen]

An SL entry consists of the entry info and the component area.
The entry info should take up 5 bytes instead of sizeof (*entry).
The area after the first 5 bytes is the component area. It is
incorrect to use the sizeof (*entry) to check the entry boundary.

Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
Reviewed-by: Thomas Schmitt <scdbackup@gmx.net>
---
 grub-core/fs/iso9660.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/grub-core/fs/iso9660.c b/grub-core/fs/iso9660.c
index c6d65fc22..ca45b3424 100644
--- a/grub-core/fs/iso9660.c
+++ b/grub-core/fs/iso9660.c
@@ -663,10 +663,23 @@ susp_iterate_dir (struct grub_iso9660_susp_entry *entry,
   else if (grub_strncmp ("SL", (char *) entry->sig, 2) == 0)
     {
       unsigned int pos = 1;
+      unsigned int csize;
 
-      /* The symlink is not stored as a POSIX symlink, translate it.  */
-      while (pos + sizeof (*entry) < entry->len)
+      /* The symlink is not stored as a POSIX symlink, translate it. */
+      while ((pos + GRUB_ISO9660_SUSP_HEADER_SZ + 1) < entry->len)
        {
+         /*
+          * entry->len is GRUB_ISO9660_SUSP_HEADER_SZ + 1 (the FLAGS)
+          * + length of the "Component Area". The length of a component
+          * record is 2 (pos and pos + 1) plus the "Component Content",
+          * of which starts at pos + 2. entry->data[pos] is the
+          * 'Component Flags'; entry->data[pos + 1] is the length
+          * of the component.
+          */
+          csize = entry->data[pos + 1] + 2;
+          if (GRUB_ISO9660_SUSP_HEADER_SZ + 1 + csize > entry->len)
+            break;
+
          /* The current position is the `Component Flag'.  */
          switch (entry->data[pos] & 30)
            {
-- 
2.35.1