1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
|
auths/spa: fix for CVE-2020-12783
This is a combined patch of git commits:
57aa14b216432be381b6295c312065b2fd034f86
a04174dc2a84ae1008c23b6a7109e7fa3fb7b8b0
leaving out whitespace noise for a smaller patch
and made it apply to the 4.93 release
modified paths because Exim dists differ in layout from the git repo
Fix SPA authenticator, checking client-supplied data before using it. Bug 2571
Rework SPA fix to avoid overflows. Bug 2571
--- a/src/auths/auth-spa.c
+++ b/src/auths/auth-spa.c
@@ -405,7 +405,7 @@ int
/* base 64 to raw bytes in quasi-big-endian order, returning count of bytes */
{
int len = 0;
- register uschar digit1, digit2, digit3, digit4;
+ uschar digit1, digit2, digit3, digit4;
if (in[0] == '+' && in[1] == ' ')
in += 2;
--- a/src/auths/spa.c
+++ b/src/auths/spa.c
@@ -139,7 +139,8 @@ SPAAuthChallenge challenge;
SPAAuthResponse response;
SPAAuthResponse *responseptr = &response;
uschar msgbuf[2048];
-uschar *clearpass;
+uschar *clearpass, *s;
+unsigned off;
/* send a 334, MS Exchange style, and grab the client's request,
unless we already have it via an initial response. */
@@ -194,9 +195,19 @@ that causes failure if the size of msgbuf is exceeded. ****/
{
int i;
- char *p = ((char*)responseptr) + IVAL(&responseptr->uUser.offset,0);
+ char * p;
int len = SVAL(&responseptr->uUser.len,0)/2;
+ if ( (off = IVAL(&responseptr->uUser.offset,0)) >= sizeof(SPAAuthResponse)
+ || len >= sizeof(responseptr->buffer)/2
+ || (p = (CS responseptr) + off) + len*2 >= CS (responseptr+1)
+ )
+ {
+ DEBUG(D_auth)
+ debug_printf("auth_spa_server(): bad uUser spec in response\n");
+ return FAIL;
+ }
+
if (len + 1 >= sizeof(msgbuf)) return FAIL;
for (i = 0; i < len; ++i)
{
@@ -245,12 +256,16 @@ spa_smb_nt_encrypt(clearpass, challenge.challengeData, ntRespData);
/* compare NT hash (LM may not be available) */
-if (memcmp(ntRespData,
- ((unsigned char*)responseptr)+IVAL(&responseptr->ntResponse.offset,0),
- 24) == 0)
- /* success. we have a winner. */
- {
+off = IVAL(&responseptr->ntResponse.offset,0);
+if (off >= sizeof(SPAAuthResponse) - 24)
+ {
+ DEBUG(D_auth)
+ debug_printf("auth_spa_server(): bad ntRespData spec in response\n");
+ return FAIL;
+ }
+s = (US responseptr) + off;
+
+if (memcmp(ntRespData, s, 24) == 0)
return auth_check_serv_cond(ablock);
- }
/* Expand server_condition as an authorization check (PH) */
|
