|
 |
bf0270 |
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
|
|
bf0270 |
From: Daniel Axtens <dja@axtens.net>
|
|
|
bf0270 |
Date: Thu, 16 Sep 2021 01:29:54 +1000
|
|
|
bf0270 |
Subject: [PATCH] net/dns: Fix double-free addresses on corrupt DNS response
|
|
|
bf0270 |
|
|
|
bf0270 |
grub_net_dns_lookup() takes as inputs a pointer to an array of addresses
|
|
|
bf0270 |
("addresses") for the given name, and pointer to a number of addresses
|
|
|
bf0270 |
("naddresses"). grub_net_dns_lookup() is responsible for allocating
|
|
|
bf0270 |
"addresses", and the caller is responsible for freeing it if
|
|
|
bf0270 |
"naddresses" > 0.
|
|
|
bf0270 |
|
|
|
bf0270 |
The DNS recv_hook will sometimes set and free the addresses array,
|
|
|
bf0270 |
for example if the packet is too short:
|
|
|
bf0270 |
|
|
|
bf0270 |
if (ptr + 10 >= nb->tail)
|
|
|
bf0270 |
{
|
|
|
bf0270 |
if (!*data->naddresses)
|
|
|
bf0270 |
grub_free (*data->addresses);
|
|
|
bf0270 |
grub_netbuff_free (nb);
|
|
|
bf0270 |
return GRUB_ERR_NONE;
|
|
|
bf0270 |
}
|
|
|
bf0270 |
|
|
|
bf0270 |
Later on the nslookup command code unconditionally frees the "addresses"
|
|
|
bf0270 |
array. Normally this is fine: the array is either populated with valid
|
|
|
bf0270 |
data or is NULL. But in these sorts of error cases it is neither NULL
|
|
|
bf0270 |
nor valid and we get a double-free.
|
|
|
bf0270 |
|
|
|
bf0270 |
Only free "addresses" if "naddresses" > 0.
|
|
|
bf0270 |
|
|
|
bf0270 |
It looks like the other use of grub_net_dns_lookup() is not affected.
|
|
|
bf0270 |
|
|
|
bf0270 |
Signed-off-by: Daniel Axtens <dja@axtens.net>
|
|
|
bf0270 |
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
|
|
|
bf0270 |
(cherry picked from commit eb2e69fcf51307757e43f55ee8c9354d1ee42dd1)
|
|
|
bf0270 |
(cherry picked from commit d801a27e7acec6c1a83067fab0bb975877eaf704)
|
|
|
bf0270 |
(cherry picked from commit 4d8b6e36ddfda4084e370b3b08c432e8a462e9be)
|
|
|
bf0270 |
---
|
|
|
bf0270 |
grub-core/net/dns.c | 6 ++++--
|
|
|
bf0270 |
1 file changed, 4 insertions(+), 2 deletions(-)
|
|
|
bf0270 |
|
|
|
bf0270 |
diff --git a/grub-core/net/dns.c b/grub-core/net/dns.c
|
|
|
bf0270 |
index 906ec7d678..135faac035 100644
|
|
|
bf0270 |
--- a/grub-core/net/dns.c
|
|
|
bf0270 |
+++ b/grub-core/net/dns.c
|
|
|
bf0270 |
@@ -667,9 +667,11 @@ grub_cmd_nslookup (struct grub_command *cmd __attribute__ ((unused)),
|
|
|
bf0270 |
grub_net_addr_to_str (&addresses[i], buf);
|
|
|
bf0270 |
grub_printf ("%s\n", buf);
|
|
|
bf0270 |
}
|
|
|
bf0270 |
- grub_free (addresses);
|
|
|
bf0270 |
if (naddresses)
|
|
|
bf0270 |
- return GRUB_ERR_NONE;
|
|
|
bf0270 |
+ {
|
|
|
bf0270 |
+ grub_free (addresses);
|
|
|
bf0270 |
+ return GRUB_ERR_NONE;
|
|
|
bf0270 |
+ }
|
|
|
bf0270 |
return grub_error (GRUB_ERR_NET_NO_DOMAIN, N_("no DNS record found"));
|
|
|
bf0270 |
}
|
|
|
bf0270 |
|