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malloc: Use overflow checking primitives where we do complex allocations

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This attempts to fix the places where we do the following where
arithmetic_expr may include unvalidated data:

  X = grub_malloc(arithmetic_expr);

It accomplishes this by doing the arithmetic ahead of time using grub_add(),
grub_sub(), grub_mul() and testing for overflow before proceeding.

Among other issues, this fixes:
  - allocation of integer overflow in grub_video_bitmap_create()
    reported by Chris Coulson,
  - allocation of integer overflow in grub_png_decode_image_header()
    reported by Chris Coulson,
  - allocation of integer overflow in grub_squash_read_symlink()
    reported by Chris Coulson,
  - allocation of integer overflow in grub_ext2_read_symlink()
    reported by Chris Coulson,
  - allocation of integer overflow in read_section_as_string()
    reported by Chris Coulson.

Fixes: CVE-2020-14309, CVE-2020-14310, CVE-2020-14311

Signed-off-by: Peter Jones <pjones@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Peter Jones 2020-06-15 12:28:27 -04:00 • committed by Daniel Kiper
parent f725fa7cb2
commit 3f05d693d1
23 changed files with 382 additions and 113 deletions
Download patch file Download diff file Expand all files Collapse all files

20
grub-core/lib/arg.c
View file

@ -23,6 +23,7 @@
#include <grub/term.h>
#include <grub/extcmd.h>
#include <grub/i18n.h>
#include <grub/safemath.h>
/* Built-in parser for default options. */
static const struct grub_arg_option help_options[] =
@ -216,7 +217,13 @@ static inline grub_err_t
add_arg (char ***argl, int *num, char *s)
{
char **p = *argl;
*argl = grub_realloc (*argl, (++(*num) + 1) * sizeof (char *));
grub_size_t sz;
if (grub_add (++(*num), 1, &sz) ||
grub_mul (sz, sizeof (char *), &sz))
return grub_error (GRUB_ERR_OUT_OF_RANGE, N_("overflow is detected"));
*argl = grub_realloc (*argl, sz);
if (! *argl)
{
grub_free (p);
@ -431,6 +438,7 @@ grub_arg_list_alloc(grub_extcmd_t extcmd, int argc,
grub_size_t argcnt;
struct grub_arg_list *list;
const struct grub_arg_option *options;
grub_size_t sz0, sz1;
options = extcmd->options;
if (! options)
@ -443,7 +451,15 @@ grub_arg_list_alloc(grub_extcmd_t extcmd, int argc,
argcnt += ((grub_size_t) argc + 1) / 2 + 1; /* max possible for any option */
}
list = grub_zalloc (sizeof (*list) * i + sizeof (char*) * argcnt);
if (grub_mul (sizeof (*list), i, &sz0) ||
grub_mul (sizeof (char *), argcnt, &sz1) ||
grub_add (sz0, sz1, &sz0))
{
grub_error (GRUB_ERR_OUT_OF_RANGE, N_("overflow is detected"));
return 0;
}
list = grub_zalloc (sz0);
if (! list)
return 0;