r11799: Added OpenSSH fix for "%.*s" format crash. From Darren Tucker

<dtucker@zip.com.au>
Jeremy.
(This used to be commit b7dee71f26b26e2aed4124c7de52fa6771ce40dd)

1 files changed, 22 insertions, 1 deletions

diff --git a/source3/lib/snprintf.c b/source3/lib/snprintf.c
index 633517def2..a3e4b06d47 100644
--- a/source3/lib/snprintf.c
+++ b/source3/lib/snprintf.c
@@ -89,6 +89,12 @@
  *
  *    Move #endif to make sure VA_COPY, LDOUBLE, etc are defined even
  *    if the C library has some snprintf functions already.
+ *
+ * Darren Tucker (dtucker@zip.com.au)
+ *    Fix bug allowing read overruns of the source string with "%.*s"
+ *    Usually harmless unless the read runs outside the process' allocation
+ *    (eg if your malloc does guard pages) in which case it will segfault.
+ *    From OpenSSH.  Also added test for same.
  **************************************************************/
 
 #ifndef NO_CONFIG_H
@@ -479,7 +485,7 @@ static void fmtstr(char *buffer, size_t *currlen, size_t maxlen,
 		value = "<NULL>";
 	}
 
-	for (strln = 0; value[strln]; ++strln); /* strlen */
+	for (strln = 0; strln < max && value[strln]; ++strln); /* strlen */
 	padlen = min - strln;
 	if (padlen < 0) 
 		padlen = 0;
@@ -892,6 +898,7 @@ int smb_snprintf(char *str,size_t count,const char *fmt,...)
 {
 	char buf1[1024];
 	char buf2[1024];
+	char *buf3;
 	char *fp_fmt[] = {
 		"%1.1f",
 		"%-1.5f",
@@ -1001,6 +1008,20 @@ int smb_snprintf(char *str,size_t count,const char *fmt,...)
 		}
 	}
 
+#define BUFSZ 2048
+
+	if ((buf3 = malloc(BUFSZ)) == NULL) {
+		fail++;
+	} else {
+		num++;
+		memset(buf3, 'a', BUFSZ);
+		snprintf(buf1, sizeof(buf1), "%.*s", 1, buf3);
+		if (strcmp(buf1, "a") != 0) {
+			printf("length limit buf1 '%s' expected 'a'\n", buf1);
+			fail++;
+		}
+        }
+
 	printf ("%d tests failed out of %d.\n", fail, num);
 
 	printf("seeing how many digits we support\n");