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fs/tar: Integer overflow leads to heap OOB write

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Both namesize and linksize are derived from hd.size, a 12-digit octal
number parsed by read_number(). Later direct arithmetic calculation like
"namesize + 1" and "linksize + 1" may exceed the maximum value of
grub_size_t leading to heap OOB write. This patch fixes the issue by
using grub_add() and checking for an overflow.

Fixes: CVE-2024-45780

Reported-by: Nils Langius <nils@langius.de>
Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Alec Brown <alec.r.brown@oracle.com>
This commit is contained in:
Lidong Chen 2024-11-22 06:27:58 +00:00 committed by Daniel Kiper
parent 2c8ac08c99
commit 0087bc6902
1 changed files with 18 additions and 5 deletions
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23
grub-core/fs/tar.c
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@ -25,6 +25,7 @@
#include <grub/mm.h>
#include <grub/dl.h>
#include <grub/i18n.h>
#include <grub/safemath.h>
GRUB_MOD_LICENSE ("GPLv3+");
@ -76,6 +77,7 @@ grub_cpio_find_file (struct grub_archelp_data *data, char **name,
{
struct head hd;
int reread = 0, have_longname = 0, have_longlink = 0;
grub_size_t sz;
data->hofs = data->next_hofs;
*name = NULL;
@ -98,7 +100,11 @@ grub_cpio_find_file (struct grub_archelp_data *data, char **name,
{
grub_err_t err;
grub_size_t namesize = read_number (hd.size, sizeof (hd.size));
*name = grub_malloc (namesize + 1);
if (grub_add (namesize, 1, &sz))
return grub_error (GRUB_ERR_BAD_FS, N_("name size overflow"));
*name = grub_malloc (sz);
if (*name == NULL)
return grub_errno;
err = grub_disk_read (data->disk, 0,
@ -118,15 +124,19 @@ grub_cpio_find_file (struct grub_archelp_data *data, char **name,
{
grub_err_t err;
grub_size_t linksize = read_number (hd.size, sizeof (hd.size));
if (data->linkname_alloc < linksize + 1)
if (grub_add (linksize, 1, &sz))
return grub_error (GRUB_ERR_BAD_FS, N_("link size overflow"));
if (data->linkname_alloc < sz)
{
char *n;
n = grub_calloc (2, linksize + 1);
n = grub_calloc (2, sz);
if (!n)
return grub_errno;
grub_free (data->linkname);
data->linkname = n;
data->linkname_alloc = 2 * (linksize + 1);
data->linkname_alloc = 2 * (sz);
}
err = grub_disk_read (data->disk, 0,
@ -149,7 +159,10 @@ grub_cpio_find_file (struct grub_archelp_data *data, char **name,
while (extra_size < sizeof (hd.prefix)
&& hd.prefix[extra_size])
extra_size++;
*name = grub_malloc (sizeof (hd.name) + extra_size + 2);
if (grub_add (sizeof (hd.name) + 2, extra_size, &sz))
return grub_error (GRUB_ERR_BAD_FS, N_("long name size overflow"));
*name = grub_malloc (sz);
if (*name == NULL)
return grub_errno;
if (hd.prefix[0])