From 1af0defd43415f15ccc26d14d8f79ff53c67d57c Mon Sep 17 00:00:00 2001
From: Guy Harris <guy@alum.mit.edu>
Date: Wed, 22 Oct 2014 12:31:21 -0700
Subject: [PATCH] Do bounds checking when unescaping PPP.
Clean up a const issue while we're at it.
---
print-ppp.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/print-ppp.c b/print-ppp.c
index ea8e00b..c1eb455 100644
--- a/print-ppp.c
+++ b/print-ppp.c
@@ -1266,11 +1266,15 @@ trunc:
static void
ppp_hdlc(const u_char *p, int length)
{
- u_char *b, *s, *t, c;
+ u_char *b, *t, c;
+ const u_char *s;
int i, proto;
const void *se;
- b = (u_int8_t *)malloc(length);
+ if (length <= 0)
+ return;
+
+ b = (u_char *)malloc(length);
if (b == NULL)
return;
@@ -1279,14 +1283,13 @@ ppp_hdlc(const u_char *p, int length)
* Do this so that we dont overwrite the original packet
* contents.
*/
- for (s = (u_char *)p, t = b, i = length; i > 0; i--) {
+ for (s = p, t = b, i = length; i > 0 && TTEST(*s); i--) {
c = *s++;
if (c == 0x7d) {
- if (i > 1) {
- i--;
- c = *s++ ^ 0x20;
- } else
- continue;
+ if (i <= 1 || !TTEST(*s))
+ break;
+ i--;
+ c = *s++ ^ 0x20;
}
*t++ = c;
}
--
1.8.3.1