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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
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9
grub-core/net/dns.c
View file

@ -22,6 +22,7 @@
#include <grub/i18n.h>
#include <grub/err.h>
#include <grub/time.h>
#include <grub/safemath.h>
struct dns_cache_element
{
@ -51,9 +52,15 @@ grub_net_add_dns_server (const struct grub_net_network_level_address *s)
{
int na = dns_servers_alloc * 2;
struct grub_net_network_level_address *ns;
grub_size_t sz;
if (na < 8)
na = 8;
ns = grub_realloc (dns_servers, na * sizeof (ns[0]));
if (grub_mul (na, sizeof (ns[0]), &sz))
return GRUB_ERR_OUT_OF_RANGE;
ns = grub_realloc (dns_servers, sz);
if (!ns)
return grub_errno;
dns_servers_alloc = na;