releases/4.14.69/livepatch-validate-module-old-func-name-length.patch

   1 From 6e9df95b76cad18f7b217bdad7bb8a26d63b8c47 Mon Sep 17 00:00:00 2001
   2 From: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
   3 Date: Fri, 20 Jul 2018 15:16:42 +0530
   4 Subject: livepatch: Validate module/old func name length
   5
   6 From: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
   7
   8 commit 6e9df95b76cad18f7b217bdad7bb8a26d63b8c47 upstream.
   9
  10 livepatch module author can pass module name/old function name with more
  11 than the defined character limit. With obj->name length greater than
  12 MODULE_NAME_LEN, the livepatch module gets loaded but waits forever on
  13 the module specified by obj->name to be loaded. It also populates a /sys
  14 directory with an untruncated object name.
  15
  16 In the case of funcs->old_name length greater then KSYM_NAME_LEN, it
  17 would not match against any of the symbol table entries. Instead loop
  18 through the symbol table comparing them against a nonexisting function,
  19 which can be avoided.
  20
  21 The same issues apply, to misspelled/incorrect names. At least gatekeep
  22 the modules with over the limit string length, by checking for their
  23 length during livepatch module registration.
  24
  25 Cc: stable@vger.kernel.org
  26 Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
  27 Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
  28 Signed-off-by: Jiri Kosina <jkosina@suse.cz>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  30
  31 ---
  32  kernel/livepatch/core.c |    6 ++++++
  33  1 file changed, 6 insertions(+)
  34
  35 --- a/kernel/livepatch/core.c
  36 +++ b/kernel/livepatch/core.c
  37 @@ -605,6 +605,9 @@ static int klp_init_func(struct klp_obje
  38         if (!func->old_name || !func->new_func)
  39                 return -EINVAL;
  40
  41 +       if (strlen(func->old_name) >= KSYM_NAME_LEN)
  42 +               return -EINVAL;
  43 +
  44         INIT_LIST_HEAD(&func->stack_node);
  45         func->patched = false;
  46         func->transition = false;
  47 @@ -678,6 +681,9 @@ static int klp_init_object(struct klp_pa
  48         if (!obj->funcs)
  49                 return -EINVAL;
  50
  51 +       if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN)
  52 +               return -EINVAL;
  53 +
  54         obj->patched = false;
  55         obj->mod = NULL;
  56