From: Antonio Quartulli <anto...@open-mesh.com>
The problem is visible when compiling with -O2:
ntlm.c: In function ‘ntlm_phase_3’:
ntlm.c:305:9: warning: dereferencing type-punned pointer will break
strict-aliasing rules [-Wstrict-aliasing]
if ((*((long *)&buf2[0x14]) & 0x00800000) == 0x00800000)
The spec suggests to interpret those 4 bytes as a long, but
this needs to be done carefully.
Signed-off-by: Antonio Quartulli <anto...@openvpn.net>
---
v2: remove htonl/ntohl conversion as there is none in the original code
src/openvpn/ntlm.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/src/openvpn/ntlm.c b/src/openvpn/ntlm.c
index 167c10b8..658c875e 100644
--- a/src/openvpn/ntlm.c
+++ b/src/openvpn/ntlm.c
@@ -302,7 +302,19 @@ ntlm_phase_3(const struct http_proxy_info *p, const char
*phase_2,
/* Add target information block to the blob */
/* Check for Target Information block */
- if ((*((long *)&buf2[0x14]) & 0x00800000) == 0x00800000)
+ /* The NTLM spec instructs to interpret these 4 consecutive bytes as a
+ * 32bit long integer. However, no endianness is specified.
+ * The code here and that found in other NTLM implementations point
+ * towards the assumption that the byte order on the wire has to
+ * match the order on the sending and receiving hosts. Probably NTLM
has
+ * been thought to be always running on x86_64/i386 machine thus
+ * implying Little-Endian everywhere.
+ *
+ * This said, in case of future changes, we should keep in mind that
the
+ * byte order on the wire for the NTLM header is LE.
+ */
+ unsigned long *flags = (unsigned long *)(buf2 + 0x14);
+ if ((*flags & 0x00800000) == 0x00800000)
{
tib_len = buf2[0x28]; /* Get Target Information block
size */
if (tib_len > 96)
--
2.14.0
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