|
 |
b35c50 |
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
|
|
b35c50 |
From: Daniel Axtens <dja@axtens.net>
|
|
|
b35c50 |
Date: Mon, 20 Dec 2021 21:55:43 +1100
|
|
|
b35c50 |
Subject: [PATCH] net/dns: Don't read past the end of the string we're checking
|
|
|
b35c50 |
against
|
|
|
b35c50 |
|
|
|
b35c50 |
I don't really understand what's going on here but fuzzing found
|
|
|
b35c50 |
a bug where we read past the end of check_with. That's a C string,
|
|
|
b35c50 |
so use grub_strlen() to make sure we don't overread it.
|
|
|
b35c50 |
|
|
|
b35c50 |
Signed-off-by: Daniel Axtens <dja@axtens.net>
|
|
|
b35c50 |
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
|
|
|
b35c50 |
(cherry picked from commit 6a97b3f4b1d5173aa516edc6dedbc63de7306d21)
|
|
|
b35c50 |
---
|
|
|
b35c50 |
grub-core/net/dns.c | 19 ++++++++++++++++---
|
|
|
b35c50 |
1 file changed, 16 insertions(+), 3 deletions(-)
|
|
|
b35c50 |
|
|
|
b35c50 |
diff --git a/grub-core/net/dns.c b/grub-core/net/dns.c
|
|
|
b35c50 |
index 135faac035..17961a9f18 100644
|
|
|
b35c50 |
--- a/grub-core/net/dns.c
|
|
|
b35c50 |
+++ b/grub-core/net/dns.c
|
|
|
b35c50 |
@@ -146,11 +146,18 @@ check_name_real (const grub_uint8_t *name_at, const grub_uint8_t *head,
|
|
|
b35c50 |
int *length, char *set)
|
|
|
b35c50 |
{
|
|
|
b35c50 |
const char *readable_ptr = check_with;
|
|
|
b35c50 |
+ int readable_len;
|
|
|
b35c50 |
const grub_uint8_t *ptr;
|
|
|
b35c50 |
char *optr = set;
|
|
|
b35c50 |
int bytes_processed = 0;
|
|
|
b35c50 |
if (length)
|
|
|
b35c50 |
*length = 0;
|
|
|
b35c50 |
+
|
|
|
b35c50 |
+ if (readable_ptr != NULL)
|
|
|
b35c50 |
+ readable_len = grub_strlen (readable_ptr);
|
|
|
b35c50 |
+ else
|
|
|
b35c50 |
+ readable_len = 0;
|
|
|
b35c50 |
+
|
|
|
b35c50 |
for (ptr = name_at; ptr < tail && bytes_processed < tail - head + 2; )
|
|
|
b35c50 |
{
|
|
|
b35c50 |
/* End marker. */
|
|
|
b35c50 |
@@ -172,13 +179,16 @@ check_name_real (const grub_uint8_t *name_at, const grub_uint8_t *head,
|
|
|
b35c50 |
ptr = head + (((ptr[0] & 0x3f) << 8) | ptr[1]);
|
|
|
b35c50 |
continue;
|
|
|
b35c50 |
}
|
|
|
b35c50 |
- if (readable_ptr && grub_memcmp (ptr + 1, readable_ptr, *ptr) != 0)
|
|
|
b35c50 |
+ if (readable_ptr != NULL && (*ptr > readable_len || grub_memcmp (ptr + 1, readable_ptr, *ptr) != 0))
|
|
|
b35c50 |
return 0;
|
|
|
b35c50 |
if (grub_memchr (ptr + 1, 0, *ptr)
|
|
|
b35c50 |
|| grub_memchr (ptr + 1, '.', *ptr))
|
|
|
b35c50 |
return 0;
|
|
|
b35c50 |
if (readable_ptr)
|
|
|
b35c50 |
- readable_ptr += *ptr;
|
|
|
b35c50 |
+ {
|
|
|
b35c50 |
+ readable_ptr += *ptr;
|
|
|
b35c50 |
+ readable_len -= *ptr;
|
|
|
b35c50 |
+ }
|
|
|
b35c50 |
if (readable_ptr && *readable_ptr != '.' && *readable_ptr != 0)
|
|
|
b35c50 |
return 0;
|
|
|
b35c50 |
bytes_processed += *ptr + 1;
|
|
|
b35c50 |
@@ -192,7 +202,10 @@ check_name_real (const grub_uint8_t *name_at, const grub_uint8_t *head,
|
|
|
b35c50 |
if (optr)
|
|
|
b35c50 |
*optr++ = '.';
|
|
|
b35c50 |
if (readable_ptr && *readable_ptr)
|
|
|
b35c50 |
- readable_ptr++;
|
|
|
b35c50 |
+ {
|
|
|
b35c50 |
+ readable_ptr++;
|
|
|
b35c50 |
+ readable_len--;
|
|
|
b35c50 |
+ }
|
|
|
b35c50 |
ptr += *ptr + 1;
|
|
|
b35c50 |
}
|
|
|
b35c50 |
return 0;
|