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[Qemu-block] [PATCH v7 10/12] uuid: Tighten uuid parse


From: Fam Zheng
Subject: [Qemu-block] [PATCH v7 10/12] uuid: Tighten uuid parse
Date: Sun, 18 Sep 2016 10:46:25 +0800

sscanf is relatively loose (tolerate) on some invalid formats that we
should fail instead of generating a wrong uuid structure, like with
whitespaces and short strings.

Add and use a helper function to first check the format.

Signed-off-by: Fam Zheng <address@hidden>
---
 util/uuid.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/util/uuid.c b/util/uuid.c
index e05ea54..81b54c3 100644
--- a/util/uuid.c
+++ b/util/uuid.c
@@ -61,12 +61,34 @@ char *qemu_uuid_unparse_strdup(const QemuUUID *uuid)
                            uu[13], uu[14], uu[15]);
 }
 
+static bool qemu_uuid_is_valid(const char *str)
+{
+    int i;
+
+    for (i = 0; i < strlen(str); i++) {
+        const char c = str[i];
+        if (i == 8 || i == 13 || i == 18 || i == 23) {
+            if (str[i] != '-') {
+                return false;
+            }
+        } else {
+            if ((c >= '0' && c <= '9') ||
+                (c >= 'A' && c <= 'F') ||
+                (c >= 'a' && c <= 'f')) {
+                continue;
+            }
+            return false;
+        }
+    }
+    return i == 36;
+}
+
 int qemu_uuid_parse(const char *str, QemuUUID *uuid)
 {
     unsigned char *uu = &uuid->data[0];
     int ret;
 
-    if (strlen(str) != 36) {
+    if (!qemu_uuid_is_valid(str)) {
         return -1;
     }
 
-- 
2.7.4




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