jfs: don't walk off the end of ealist

commit d0fa70a upstream.

Add a check before visiting the members of ea to
make sure each ea stays within the ealist.

Signed-off-by: lei lu <llfamsec@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/jfs/xattr.c

@@ -797,7 +797,7 @@ ssize_t __jfs_getxattr(struct inode *inode, const char *name, void *data,
  size_t buf_size)
 {
  struct jfs_ea_list *ealist;
- struct jfs_ea *ea;
+ struct jfs_ea *ea, *ealist_end;
  struct ea_buffer ea_buf;
  int xattr_size;
  ssize_t size;
@@ -817,9 +817,16 @@ ssize_t __jfs_getxattr(struct inode *inode, const char *name, void *data,
  goto not_found;
 
  ealist = (struct jfs_ea_list *) ea_buf.xattr;
+ ealist_end = END_EALIST(ealist);
 
  /* Find the named attribute */
- for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist); ea = NEXT_EA(ea))
+ for (ea = FIRST_EA(ealist); ea < ealist_end; ea = NEXT_EA(ea)) {
+ if (unlikely(ea + 1 > ealist_end) ||
+ unlikely(NEXT_EA(ea) > ealist_end)) {
+ size = -EUCLEAN;
+ goto release;
+ }
+
  if ((namelen == ea->namelen) &&
  memcmp(name, ea->name, namelen) == 0) {
  /* Found it */
@@ -834,6 +841,7 @@ ssize_t __jfs_getxattr(struct inode *inode, const char *name, void *data,
  memcpy(data, value, size);
  goto release;
  }
+ }
  not_found:
  size = -ENODATA;
  release:
@@ -861,7 +869,7 @@ ssize_t jfs_listxattr(struct dentry * dentry, char *data, size_t buf_size)
  ssize_t size = 0;
  int xattr_size;
  struct jfs_ea_list *ealist;
- struct jfs_ea *ea;
+ struct jfs_ea *ea, *ealist_end;
  struct ea_buffer ea_buf;
 
  down_read(&JFS_IP(inode)->xattr_sem);
@@ -876,9 +884,16 @@ ssize_t jfs_listxattr(struct dentry * dentry, char *data, size_t buf_size)
  goto release;
 
  ealist = (struct jfs_ea_list *) ea_buf.xattr;
+ ealist_end = END_EALIST(ealist);
 
  /* compute required size of list */
- for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist); ea = NEXT_EA(ea)) {
+ for (ea = FIRST_EA(ealist); ea < ealist_end; ea = NEXT_EA(ea)) {
+ if (unlikely(ea + 1 > ealist_end) ||
+ unlikely(NEXT_EA(ea) > ealist_end)) {
+ size = -EUCLEAN;
+ goto release;
+ }
+
  if (can_list(ea))
  size += name_size(ea) + 1;
  }