1From 3328e98bcbf2930cd7eea3e6c92ad5dcbdf4794f Mon Sep 17 00:00:00 2001
2From: Yuanjie Huang <yuanjie.huang@windriver.com>
3Date: Wed, 24 Aug 2016 03:15:43 +0000
4Subject: [PATCH] Fix potential signed overflow in pointer arithmatic
5
6Pointer arithmatic results in implementation defined signed integer
7type, so that 's - src' in strlcpy and others may trigger signed overflow.
8In case of compilation by gcc or clang with -ftrapv option, the overflow
9would lead to program abort.
10
11Upstream-Status: Submitted [http://bugzilla.mindrot.org/show_bug.cgi?id=2608]
12
13Signed-off-by: Yuanjie Huang <yuanjie.huang@windriver.com>
14
15Complete the fix
16Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
17---
18 openbsd-compat/strlcat.c | 10 +++++++---
19 openbsd-compat/strlcpy.c |  8 ++++++--
20 openbsd-compat/strnlen.c |  8 ++++++--
21 3 files changed, 19 insertions(+), 7 deletions(-)
22
23diff --git a/openbsd-compat/strlcat.c b/openbsd-compat/strlcat.c
24index bcc1b61..124e1e3 100644
25--- a/openbsd-compat/strlcat.c
26+++ b/openbsd-compat/strlcat.c
27@@ -23,6 +23,7 @@
28
29 #include <sys/types.h>
30 #include <string.h>
31+#include <stdint.h>
32
33 /*
34  * Appends src to string dst of size siz (unlike strncat, siz is the
35@@ -42,7 +43,7 @@ strlcat(char *dst, const char *src, size_t siz)
36 	/* Find the end of dst and adjust bytes left but don't go past end */
37 	while (n-- != 0 && *d != '\0')
38 		d++;
39-	dlen = d - dst;
40+	dlen = (uintptr_t)d - (uintptr_t)dst;
41 	n = siz - dlen;
42
43 	if (n == 0)
44@@ -55,8 +56,11 @@ strlcat(char *dst, const char *src, size_t siz)
45 		s++;
46 	}
47 	*d = '\0';
48-
49-	return(dlen + (s - src));	/* count does not include NUL */
50+        /*
51+	 * Cast pointers to unsigned type before calculation, to avoid signed
52+	 * overflow when the string ends where the MSB has changed.
53+	 */
54+	return (dlen + ((uintptr_t)s - (uintptr_t)src));	/* count does not include NUL */
55 }
56
57 #endif /* !HAVE_STRLCAT */
58diff --git a/openbsd-compat/strlcpy.c b/openbsd-compat/strlcpy.c
59index b4b1b60..b06f374 100644
60--- a/openbsd-compat/strlcpy.c
61+++ b/openbsd-compat/strlcpy.c
62@@ -23,6 +23,7 @@
63
64 #include <sys/types.h>
65 #include <string.h>
66+#include <stdint.h>
67
68 /*
69  * Copy src to string dst of size siz.  At most siz-1 characters
70@@ -51,8 +52,11 @@ strlcpy(char *dst, const char *src, size_t siz)
71 		while (*s++)
72 			;
73 	}
74-
75-	return(s - src - 1);	/* count does not include NUL */
76+        /*
77+	 * Cast pointers to unsigned type before calculation, to avoid signed
78+	 * overflow when the string ends where the MSB has changed.
79+	 */
80+	return ((uintptr_t)s - (uintptr_t)src - 1);	/* count does not include NUL */
81 }
82
83 #endif /* !HAVE_STRLCPY */
84diff --git a/openbsd-compat/strnlen.c b/openbsd-compat/strnlen.c
85index 7ad3573..7040f1f 100644
86--- a/openbsd-compat/strnlen.c
87+++ b/openbsd-compat/strnlen.c
88@@ -23,6 +23,7 @@
89 #include <sys/types.h>
90
91 #include <string.h>
92+#include <stdint.h>
93
94 size_t
95 strnlen(const char *str, size_t maxlen)
96@@ -31,7 +32,10 @@ strnlen(const char *str, size_t maxlen)
97
98 	for (cp = str; maxlen != 0 && *cp != '\0'; cp++, maxlen--)
99 		;
100-
101-	return (size_t)(cp - str);
102+        /*
103+	 * Cast pointers to unsigned type before calculation, to avoid signed
104+	 * overflow when the string ends where the MSB has changed.
105+	 */
106+	return (size_t)((uintptr_t)cp - (uintptr_t)str);
107 }
108 #endif
109--
1102.17.1
111
112